全文获取类型
收费全文 | 139549篇 |
免费 | 1021篇 |
国内免费 | 75篇 |
专业分类
耳鼻咽喉 | 4469篇 |
儿科学 | 4706篇 |
妇产科学 | 5869篇 |
基础医学 | 25456篇 |
口腔科学 | 3415篇 |
临床医学 | 6305篇 |
内科学 | 28719篇 |
皮肤病学 | 6216篇 |
神经病学 | 9586篇 |
特种医学 | 6014篇 |
外科学 | 22185篇 |
综合类 | 471篇 |
一般理论 | 4篇 |
预防医学 | 4723篇 |
眼科学 | 5540篇 |
药学 | 4605篇 |
2篇 | |
中国医学 | 47篇 |
肿瘤学 | 2313篇 |
出版年
2015年 | 3328篇 |
2014年 | 3930篇 |
2013年 | 5184篇 |
2012年 | 3798篇 |
2011年 | 3587篇 |
2010年 | 3932篇 |
2009年 | 4004篇 |
2008年 | 3859篇 |
2007年 | 3745篇 |
2006年 | 4195篇 |
2005年 | 3671篇 |
2004年 | 3363篇 |
2003年 | 1756篇 |
1999年 | 925篇 |
1998年 | 1207篇 |
1997年 | 1223篇 |
1996年 | 1624篇 |
1995年 | 1792篇 |
1994年 | 1832篇 |
1993年 | 1723篇 |
1992年 | 1794篇 |
1991年 | 1551篇 |
1990年 | 1400篇 |
1989年 | 1267篇 |
1988年 | 1144篇 |
1987年 | 1228篇 |
1986年 | 1163篇 |
1985年 | 995篇 |
1984年 | 1090篇 |
1983年 | 893篇 |
1982年 | 1095篇 |
1981年 | 1000篇 |
1980年 | 968篇 |
1979年 | 1001篇 |
1978年 | 1144篇 |
1977年 | 888篇 |
1973年 | 907篇 |
1934年 | 881篇 |
1933年 | 1493篇 |
1932年 | 1483篇 |
1931年 | 1472篇 |
1930年 | 1652篇 |
1929年 | 1389篇 |
1928年 | 1530篇 |
1927年 | 1497篇 |
1926年 | 1583篇 |
1925年 | 1544篇 |
1924年 | 1611篇 |
1923年 | 1465篇 |
1922年 | 1442篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
Burger AM 《BioDrugs : clinical immunotherapeutics, biopharmaceuticals and gene therapy》1999,12(6):413-422
Curing cancers is one of the most challenging tasks of modern medicine. The major problem is the heterogeneity of human tumours and thus finding a 'universal' target for cancer treatment. The discovery that the expression of the enzyme telomerase is a hallmark of immortality and cancer, and that it is found in the majority (>85%) of human tumours but is repressed in most normal cells, has therefore caused considerable excitement. These observations led to the design of potential telomerase inhibitors and ideas about targeting telomerase in the clinic. To date, several classes of telomerase inhibitory agents have been identified and are in preclinical development. However, the approach has not yet been tested clinically. Because of the proposed function of telomerase, and the understanding that replicative cell senescence or cell death result from progressive telomere shortening during successive cell divisions, even complete enzyme inhibition will not produce immediate cell death. Designing clinical trials for promising telomerase inhibitors requires consideration of the novel mechanism of action of these drugs. A lag period between initiation of treatment and occurrence of effects is likely, and thus anti-telomerase therapy might best be given in adjuvant treatment protocols after initial tumour debulking therapy and in combination with other cytostatic agents. The available knowledge of telomerase biology and its association with human tumours suggests that telomerase inhibition might prove a valuable addition to current cancer treatment regimens. 相似文献
992.
Wehrmeyer JA Barthel JA Roth JP Saifuddin T 《Medical & biological engineering & computing》1998,36(4):475-479
A testing device is developed that determines the stiffness, or flexural rigidity, of an endoscope at specific locations down
its length by subjecting it to a compressive axial force, a situation similar to the actual forces applied to the endoscope
during a clinical procedure. The endoscope is made to deform in a similar fashion to a slender buckled column and the force
causing this deformation is related to the flexural rigidity using column buckling theory. A direct relationship between the
critical load needed to cause buckling and the square of column length L is demonstrated experimentally and is expected theoretically,
giving confidence in the application of column buckling theory to endoscope testing. Additional confidence in the validity
of the columnbuckling test results is obtained by their similarity to data obtained by subjecting the endoscope to a transverse
load, determining deflection, and modelling the endoscope as a bent elastic beam. Several makes and models of endoscopes were
tested, with flexural rigidity values typically ranging between 160 to 240 Ncm2. The effect of a metal stiffener inserted in an endoscope's accessory channel is quantified, as is the change in flexural
rigidity down the insertion shaft of a graded-stiffness endoscope. Significant differences in flexural rigidity were obtained
between identical endoscopes, each sharing similar usage histories, indicating the need for flexural rigidity measurements
for each individual endoscope of a particular model line, though a more extensive study is required to reliably determine
scope-to-scope stiffness variations for a particular model line. 相似文献
993.
994.
Antibiotic Use in Crohn’s Disease 总被引:3,自引:0,他引:3
Prantera C Scribano ML Berto E Zannoni F 《BioDrugs : clinical immunotherapeutics, biopharmaceuticals and gene therapy》1997,8(4):293-306
On the assumption that bacteria in the gut may be a cause of symptoms and/or complications of Crohn's disease, various antibiotics are efficaciously employed in some affected patients. However, we do not know exactly why and how they are helpful. A possible explanation is that one or several bacterial species may have a primary role in the aetiology of Crohn's disease, but this is not supported by the data in our possession. Another hypothesis is that intestinal bacteria may cause flare-up of the disorder, either by inducing intestinal lesions or by an interaction with the immune system, but we know today that specific pathogens can cause flares only in a minority of cases. On the contrary, there is considerable evidence that the intestinal microflora and its products may amplify and perpetuate inflammation in Crohn's disease. Despite the fact that few controlled trials have been conducted, and have shown inconclusive results, antibiotics are widely employed for improving symptoms and for inducing remission of active phases. At present, a combination of metronidazole and ciprofloxacin, active against many enteric bacteria, has proved to be effective in the treatment of Crohn's disease complications. This therapy also seems to be effective in acute flares as an alternative to, or in combination with, corticosteroids. 相似文献
995.
Gert Baumann Stephan B. Felix Claus D. Heidecke Gotthard Rieß Ursula Loher Liesel Ludwig Prof. Dr Hans Blömer 《Inflammation research》1984,15(3-4):216-228
Left ventricular infarction (AMI) was produced in experimental animals and the contractile response to -adrenergic and H2-histaminergic stimulation by isoproterenol and impromidine tested in the isolated perfused heart preparation. Adenylate cyclase activity as well as binding characteristics of [3H]-dihydroalprenolol ([3H]-DHA), [3H]-methyl-tiotidine ([3H]-TIOT) and [3H]-quinuclidinyl benzilate ([3H]-QNB) to cardiac
1-, H2- and cholinergic muscarinic receptors were determined in sarcolemmal membrane preparations of the right ventricle of the same hearts. In addition, an attempt was made to elucidate the therapeutic value of post-AMI treatment with impromidine in the presence and absence of-sympathomimetic, in contrast to administration of prenalterol and the conventional therapy with -sympathomimetic drugs, e.g. dobutamine. Three days post-AMI the dose-response curve for isoproterenol of right ventriculardP/dt
max was significantly depressed, while the inotropic effect of impromidine was not impaired. Stimulation of adenylate cyclase activity by isoproterenol was reduced by 80% whereas impromidine and NaF stimulation rates were unaltered. Receptor-binding studies indicated a 90% loss and 10-times lowered affinity (K
D) of the remaining -receptors while specific [3H]-TIOT- and [3H]-QNB-binding was unchanged.Administration of dobutamine increased mortality rates and extension of infarct size, led to a further decrease in contractile response to isoproterenol, induced complete insensitivity of adenylate cyclase to isoproterenol stimulation and caused pronounced additional reduction of number and affinity of [3H]-DHA-binding sites. In contrast, all above alterations were prevented by treatment with either prenalterol or combined administration of impromidine plus metoprolol. It is concluded, that these alterations in the non-ischemic, uninvolved myocardium post-AMI are the result of catecholamine-induced specific damage of sarcolemmal -receptors. Furthermore, treatment with H2-agonists in combination with -blocking agents may have beneficial effects, whereas conventional therapy with -sympathomimetic drugs tends to worsen the already depressed function of the -adrenergic stimulation mechanism.Supported by grants Ba 666/1 and Ba 666/2-2 from the Deutsche Forschungsgemeinschaft (DFG).Data presented in this paper are part of a doctoral thesis by Dr S.B. Felix. 相似文献
996.
Dr. S. Shiosaka M. Tohyama H. Takagi Y. Takahashi Y. Saitoh T. Sakumoto H. Nakagawa N. Shimizu 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1980,39(4):377-388
Summary The ascending and descending components of the medial forebrain bundle (MFB) were investigated by means of horseradish peroxidase (HRP) with a sensitive substrate. The HRP was injected iontophoretically into the MFB at various levels from the anterior commissure to the posterior hypothalamus. In order to prevent the diffusion of HRP to other brain areas, a double micropipette system was used. The descending components of the MFB are derived from (1) the anterior cingulate area, infra- or prelimbic area, and sulcal cortex, (2) the lateral septal nucleus and diagonal band, (3) the bed nucleus of the stria terminalis, (4) the paraventricular nucleus (5) the substantia innominata, (6) the amygdaloid complex (AM), (7) the ventromedial (VM) and dorsomedial (DM) hypothalamic nuclei, (8) the entopeduncular nucleus and (9) nucleus periventricularis stellatocellularis. The ascending components of the MFB originate in: (1) the medial preoptic nucleus, (2) the nucleus periventricularis stellatocellularis and rotundocellularis, (3) the posterior hypothalamic nucleus, (4) the parafascicular nucleus, (5) the ventral premammillary nucleus, (6) the substantia grisea periventricularis, (7) the lateral habenular nucleus, (8) the VM and DM, (9) the paratenial nucleus, (10) the AM and (11) the arcuate nucleus.Abbreviations used in Figures and Tables a
nucleus accumbens
- abl
nucleus amygdaloideus basalis, pars lateralis
- abm
nucleus amygdaloideus basalis, pars medialis
- ac
nucleus amygdaloideus centralis
- AC
anterior cingulate area
- al
nucleus amygdaloideus lateralis
- am
nucleus amygdaloideus medialis
- ar
nucleus arcuatus
- CC
tractus corporis callosi
- CSDV
commissura supraoptica dorsalis, pars ventralis
- DB
diagonal band
- DM
nucleus dorsomedialis hypothalami
- EP
nucleus entopeduncularis
- ha
nucleus anterior hypothalami
- hl
nucleus lateralis hypothalami
- hp
nucleus posterior hypothalami
- IL
infralimbic area of frontal cortex
- lh
nucleus habenulae lateralis
- LH1
medial forebrain bundle (MFB) at the level of commissura anterior
- LH2
lateral preoptic area
- LH3
MFB at the level of the nucleus anterior hypothalami
- LH4
MFB at the level of the nucleus ventromedialis hypothalami
- LH5
MFB at the level of the nucleus posterior hypothalami
- MFB
medial forebrain bundle
- pf
nucleus parafascicularis
- PL
prelimbic area of frontal cortex
- pol
nucleus preopticus lateralis
- pom
nucleus preopticus medialis
- posc
nucleus preopticus, pars suprachiasmatica
- pt
nucleus parataenialis
- pv
nucleus premamillaris ventralis
- PV
nucleus paraventricularis
- pvs
nucleus periventricularis stellatocellularis
- pvr
nucleus periventricularis rotundocellularis
- SC
sulcal cortex
- SGPV
substantia grisea periventricularis
- SI
substantia innominata
- SL
lateral septal nucleus
- ST
bed nucleus of stria terminalis
- sum
nucleus supramamillaris
- TO
tractus opticus
- tmm
nucleus medialis thalami, pars medialis
- VM
nucleus ventromedialis hypothalami
The nomenclature used in this paper is according to König and Klippel's Stereotaxic Atlas (1967). 相似文献
997.
Dr Bernard Sénécail Bernard Menanteau Pierre Quereux 《Surgical and radiologic anatomy : SRA》1979,2(2):181-190
Résumé Ce travail tente de définir une écho-anatomie du foie normal à partir de neuf plans tomographiques de référence, chacun étant caractérisé par la morphologie de la glande hépatique, par son contenu structural et par son environnement topographique.Les auteurs interprètent l'imagerie échographique directement à partir de l'observation macroscopique de coupes anatomiques correspondantes. Ils indiquent que la corrélation anatomo-échographique est satisfaisante et dégagent quelques indications spécifiques pour chacune des incidences. 相似文献
998.
Dr. T. Mergner L. Deecke H. -J. Wagner 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1981,44(4):455-458
Summary Suggestive evidence as to the site of a major thalamic relay of the vestibular projection to the anterior suprasylvian (ASS) cortex in the cat has been obtained using the retrograde axonal transport of horseradish peroxidase. The thalamo-cortical neurons are located in several patches surrounding the posterior margins of the ventro-basal complex (VB). This area also was found to receive vestibulo-thalamic projections. It comprises different nuclear groups known to carry somatic, accoustic, visual or combined information, which possibly have certain functions related to kinaesthesia and body orientation in common.Abbreviations ANS
ansate sulcus
- ASSS
anterior suprasylvian sulcus
- CM, N
centrum medianum
- CL, N
centralis lateralis
- C.r
Corpus restiformis
- D, N
vestibularis descendens
- i.c., N
intercalatus
- L, N
vestibularis lateralis
- LD, N
lateralis dorsalis
- LG, N
geniculatus lateralis
- LP, N
lateralis posterior
- M, N
vestibularis medialis
- MG, N
geniculatus medialis
- mcMG
pars magnocellularis of MG
- MD, N
medialis dorsalis
- N.c., N
cuneatus
- N. in. VIII, N
interstitialis of the VIIIth cranial nerve
- N. pr. V
principal sensory trigeminal nucleus
- N. tr. sp. V
nucleus of the spinal trigeminal tract
- p.h., N
praepositus hypoglossi
- Pu
pulvinar
- S, N
vestibularis superior
- SG, N
suprageniculatus
- VL, N
ventralis lateralis
- VPL, N
ventralis posterolateralis
- VPM, N
ventralis posteromedialis
- VI, X, XII
motor cranial nerve nuclei
- y, z
small cell groups of Brodal and Pompeiano
Supported by Deutsche Forschungsgemeinschaft, SFB 70 相似文献
999.
Dietrich L. Meyer Dr. Detlef Bonnemann Prof. Dr. Kurt -Peter Schaefer 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1973,18(5):505-511
Summary Turning a rabbit on a turn-table for a few degrees induces compensatory eye-movements and results in an asymmetry of tonus in the optomotor system. If the visual input is discontinued (darkness), this asymmetry decays and the eyes drift back to the mid-position within 12–18 sec. The equalization of such asymmetries of tonus under normal conditions and under curare is described. Tonus asymmetries induced by tilting the animals about the longitudinal axis are neither compensated under visual, nor under non-visual, conditions. Recordings were taken from oculomotor neurons, and changes of their firing frequencies were used as a measure for eye movements.A preliminary report was given at the spring meeting of the German Physiological Society 1973.Supported by the Deutsche Forschungsgemeinschaft, SFB 33. 相似文献
1000.
Ohne ZusammenfassungHerr Professor Dr.James E. Rothman wurde 1950 in Haverhill/Mass. geboren, studierte am Yale-College und am Department of Biological Chemistry, Harvard Medical School sowie am Department of Biology, Massachusetts Inst. of Technology von 1967–1978. Daraufhin wurde er Assistant Professor, 3 Jahre später Associate Professor und nach weiteren 3 Jahren Professor am Department of Biochemistry, Stanford University. Seit 1988 ist er Squibb Professor of Molecular Biology am Department of Biology an der Princeton University.Herr Prof. Dr.K.W.A. Wirtz wurde 1942 in Utrecht geboren, erhielt seine Ausbildung in Biochemie und Physiologie an den Universitäten von Utrecht und Cornell Univ. Ithaka und promovierte mit einer Arbeit unter Prof. L.L.M. van Deenen (Heinrich-Wieland-Preis 1971). Unterbrochen durch längere Aufenthalte im Ausland, wurde er 1973 Assistant Professor und 1980 Professor für Biochemie an seiner heutigen Wirkungsstätte. 相似文献