全文获取类型
收费全文 | 1994篇 |
免费 | 137篇 |
国内免费 | 76篇 |
专业分类
耳鼻咽喉 | 7篇 |
儿科学 | 93篇 |
妇产科学 | 61篇 |
基础医学 | 217篇 |
口腔科学 | 115篇 |
临床医学 | 256篇 |
内科学 | 423篇 |
皮肤病学 | 48篇 |
神经病学 | 132篇 |
特种医学 | 290篇 |
外科学 | 173篇 |
综合类 | 41篇 |
一般理论 | 1篇 |
预防医学 | 153篇 |
眼科学 | 35篇 |
药学 | 99篇 |
中国医学 | 3篇 |
肿瘤学 | 60篇 |
出版年
2021年 | 11篇 |
2019年 | 25篇 |
2018年 | 25篇 |
2016年 | 22篇 |
2015年 | 27篇 |
2014年 | 30篇 |
2013年 | 46篇 |
2012年 | 69篇 |
2011年 | 82篇 |
2010年 | 68篇 |
2009年 | 80篇 |
2008年 | 60篇 |
2007年 | 113篇 |
2006年 | 72篇 |
2005年 | 63篇 |
2004年 | 64篇 |
2003年 | 62篇 |
2002年 | 51篇 |
2001年 | 62篇 |
2000年 | 48篇 |
1999年 | 37篇 |
1998年 | 101篇 |
1997年 | 77篇 |
1996年 | 70篇 |
1995年 | 68篇 |
1994年 | 54篇 |
1993年 | 52篇 |
1992年 | 49篇 |
1991年 | 32篇 |
1990年 | 37篇 |
1989年 | 50篇 |
1988年 | 49篇 |
1987年 | 47篇 |
1986年 | 37篇 |
1985年 | 38篇 |
1984年 | 28篇 |
1983年 | 18篇 |
1982年 | 24篇 |
1981年 | 14篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1978年 | 14篇 |
1977年 | 19篇 |
1976年 | 19篇 |
1975年 | 18篇 |
1974年 | 10篇 |
1971年 | 9篇 |
1970年 | 9篇 |
1968年 | 10篇 |
1967年 | 11篇 |
排序方式: 共有2207条查询结果,搜索用时 281 毫秒
21.
Del-Favero J; Krols L; Michalik A; Theuns J; Lofgren A; Goossens D; Wehnert A; Van den Bossche D; Van Zand K; Backhovens H; van Regenmorter N; Martin JJ; Van Broeckhoven C 《Human molecular genetics》1998,7(2):177-186
Autosomal dominant cerebellar ataxia with retinal degeneration (ADCAII) was
previously mapped by linkage analysis studies to chromosome 3p12- p21.1
(SCA7). Positional cloning efforts have recently identified a novel gene,
SCA7 , containing a translated CAG repeat, expanded in SCA7 patients. We
cloned the SCA7 gene from a yeast artificial chromosome (YAC) clone contig
spanning the SCA7 candidate region. Using a combination of genomic
sequencing and cosmid-based exon trapping, two expressed sequence tags were
identified. Sequencing of the corresponding cDNA clones and RT-PCR analysis
identified the full- length SCA7 cDNA. Together, our sequence data defined
the intron/exon boundaries of the first two coding exons of the SCA7 gene,
with the first exon containing the expanded CAG repeat. Further, sequence
comparison with the published SCA7 cDNA identified one additional putative
exon in the 5'-UTR region of the SCA7 gene. The SCA7 gene was mapped on the
YAC contig in the 2.5 cM interval between D3S1600 and D3S1287. In one
extended Belgian SCA7 pedigree the expanded alleles ranged from 38 to at
least 55 repeats with allele lengths being inversely correlated with onset
age of ADCAII symptoms. The SCA7 repeats increased in length in successive
generations. Normal alleles had from four to 18 repeats, with 10 repeats
being the most common allele.
相似文献
22.
Factors associated with the provision of anti-smoking advice in general practice consultations.
下载免费PDF全文
![点击此处可从《The British journal of general practice》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Alison Wynn Tim Coleman Stephen Barrett Andrew Wilson 《The British journal of general practice》2002,52(485):997-999
Guidelines urge general practitioners (GPs) to discuss smoking with patients as frequently as possible. Using data collected before and after consultations, this study confirms that GPs are more likely to discuss smoking in the context of smoking-related problems. Encouraging GPs to make greater use of problem-orientated opportunities to discuss smoking may have more effect on rates of advice giving than urging them to advise all smokers. 相似文献
23.
Observations on some effects of L-triiodothyronine on carbohydrate and lipid metabolism in man
下载免费PDF全文
![点击此处可从《Journal of clinical pathology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Fasting serum lipid levels and changes in plasma glucose, fatty acid non-esterified (Nefa), and blood pyruvate levels during intravenous glucose tolerance tests were measured in 13 normal subjects before and one, five, and 15 days after the administration of 1-triiodothyronine (T3) calculated as 6 mug/kg body weight.Significant increases in the mean basal metabolic rate and the mean fasting plasma Nefa level occurred within 10 to 17 hours of a single dose of T3, while a rise in the mean fasting plasma glucose concentration just failed to achieve significance. Fasting concentrations of blood pyruvate and serum triglyceride were unaffected. A significant fall in serum cholesterol levels was produced and lasted at least five days. All other indices returned to normal by five days.During intravenous glucose tolerance tests performed at intervals after T3 administration no change in plasma glucose levels from control values was seen. Mean plasma Nefa and blood pyruvate levels, however, were significantly raised above control values during the early stages of the test 10 to 17 hours after T3. The relationship between these findings and those observed in clinical thyrotoxicosis is discussed. 相似文献
24.
JJ Favre Ph Chaffanjon JG Passagia JP Chirossel 《Surgical and radiologic anatomy : SRA》1995,17(2):133-138
Summary The authors report the results of a series of dissections and anatomic sections of the fronto-basal region of the brain and of the anterior cranial fossa in human cadavers. The constant presence of an arachnoidal cistern above the olfactory nerve was verified. The arachnoid separates from the pial membrane and forms a bridge with the ventral part of the olfactory bulb and tract, from the lateral edge of the olfactory sulcus to the medial edge of the gyrus rectus. The cistern is wide in its anterior portion, between the gyrus rectus and the olfactory bulb, and is reduced to a virtual slit in its posterior portion where the tract is lodged in the olfactory sulcus. The olfactory nerve can be separated without damaging fronto-basal arachnoidial adhesions over several centimeters. Dissection of this region after intravascular injection of colored media shows the constant presence of an artery destined to the olfactory bulb and tract. It originates either from the lateral surface of the anterior cerebral a. (segment A2), or from the medial fronto-basal a., and consistently provides terminal branches in front of the olfactory trigone in the medial olfactory sulcus. At their ventral extremity, the olfactory structures are therefore vascularised independently for several centimeters, from the lower face of the frontal lobe. The independent vascularisation of the olfactory nerve, the tenuous and easily detachable adhesions, and the actual presence of a true arachnoidal cistern all contribute to enabling surgical techniques which conserve olfactory function during anterior approaches.
Vascularisation du nerf olfactif. Rapports méningés et applications chirurgicales
Résumé Les auteurs rapportent les résultats d'une série de dissections et de coupes de la région fronto-basale de l'encéphale et de la fosse crânienne antérieure sur sujets cadavériques. La présence constante d'une citerne arachnoïdienne au dessus du n. olfactif a été vérifiée. L'arachnoïde se sépare du feuillet pial et passe en pont à la partie ventrale du bulbe et du tractus olfactifs, du bord latéral du sillon olfactif au bord médial du gyrus rectus. La citerne est large dans sa portion antérieure, entre le gyrus rectus et le bulbe olfactif, se réduit à une fente virtuelle postérieure lorsque le tractus se loge dans le sillon olfactif. Le n. olfactif peut être séparé sans dommage des adhérences arachnoïdiennes fronto-basales sur quelques centimètres. La dissection de cette région, après injection intravasculaire de masses colorées montre, de façon originale, la présence constante d'une artère destinée au tractus et au bulbe olfactifs. Elle naît soit de la face latérale de l'a. cérébrale antérieure (segment A2), soit de l'a. fronto-basale médiale, pour donner ses branches terminales toujours en avant du trigone olfactif dans le sillon orbitaire médial. Sur quelques centimètres à leur extrémité ventrale, les structures olfactives ont donc une vascularisation indépendante de la face inférieure du lobe frontal. L'indépendance vasculaire du n. olfactif, des adhérences ténues, facilement détachables, et la réalité vérifiée d'une véritable citerne arachnoïdienne permettent d'imaginer des techniques conservatrices de la fonction olfactive utilisées dans plusieurs indications de la chirurgie de la fosse crânienne antérieure.相似文献
25.
The infrapyloric artery and cephalic pancreatoduodenectomy with pylorus preservation: preliminary study 总被引:1,自引:0,他引:1
Ph Wind JM Chevallier JJ Sarcy V Delmas PH Cugnenc 《Surgical and radiologic anatomy : SRA》1994,16(2):165-172
Summary Cephalic pancreatoduodenectomy (CPD) with pylorus preservation has been suggested to improve the functional and nutritional result of surgery. At operation, the first two centimeters of the duodenum are preserved, the vascular arch of the lesser gastric curvature is saved and the right gastroepiploic artery is resected at its origin. The aim of this study on 15 fresh cadavers was to determine the origin of the vascularization of the remaining duodenum and also the possibilities of preserving an optimal vascularization after CPD and pylorus preservation. All of the arteries supplying the remaining duodenum and arising either from the right gastric artery or the right gastroepiploic artery were identified. The distances between the origin of the infrapyloric artery and the termination of the gastroduodenal artery on the cranial and ventral pancreaticoduodenal artery and the left gastroepiploic artery were measured. At CPD with pylorus preservation, the study demonstrated that: 1) the cranial side of the remaining duodenum remains vascularized in 80% of the cases by one or two supraduodenal branches coming from the right gastric artery; 2) ligation of the right gastroepiploic artery eliminates all vascular supply to the caudal side of the remaining duodenum in almost half of the cases; 3) in these cases, the dissection of the bifurcation of the gastroduodenal artery and the vascular section beyond the origin of the infrapyloric artery allowed a direct vascular supply to the remaining duodenum to be preserved.This work was presented at the French Section of the European Association of Clinical Anatomy meeting, Bobigny, France, 1992 相似文献
26.
Dithiothreitol prevents age-associated decrease in oocyte/conceptus viability in vitro 总被引:2,自引:0,他引:2
The present study was designed to ascertain whether the negative effects on
reproductive potential of post-ovulatory ageing in vitro of oocytes can be
prevented by antioxidant therapy. Mouse metaphase II (MII) oocytes were
aged in vitro for 12 h prior to insemination in the presence of varying
concentrations of L-ascorbic acid, 6-methoxy-
2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), L-cystine
dihydrochloride, ethylenediaminetetraacetic acid (EDTA), beta-
mercaptoethanol and DL-dithiothreitol (DTT). In-vitro ageing of oocytes was
associated with lower fertilization rate, higher proportion of concepti
exhibiting cellular fragmentation at 24 h post-insemination and lower
percentage of concepti reaching the blastocyst stage. Ascorbic acid, Trolox
and EDTA had no effect on cellular fragmentation or potential of oocytes
for development. However, the probability of an oocyte reaching the
blastocyst stage was decreased (P < or = or = 0.05) in oocytes incubated
in the presence of L-cystine (50 and 500 microM) and beta-mercaptoethanol
(5, 50 and 500 microM) when compared to control aged oocytes.
Age-associated cellular fragmentation at 24 h post-insemination was
partially prevented (P < or = 0.05) by incubating oocytes in the
presence of beta-mercaptoethanol (500 microM). DTT (50 and 500 microM)
increased (P < or = 0.05) fertilization rate and number of cells at 81 h
post-insemination to levels similar to those exhibited by control oocytes.
Furthermore, both age-associated fragmentation at 24 h post-insemination (P
< or = 0.05) and decreased potential of oocytes for development to the
blastocyst stage (P < or = 0.05) were prevented, at least in part, by
culturing oocytes in the presence of DTT (50 microM). Although the
mechanism by which DTT exerts its beneficial effects on aged oocytes
remains to be elucidated, it may protect oocytes by preventing oxidation of
free thiol groups and/or altering a redox-independent signalling pathway
that mediates cellular fragmentation and death.
相似文献
27.
Vankeerberghen A; Wei L; Jaspers M; Cassiman JJ; Nilius B; Cuppens H 《Human molecular genetics》1998,7(11):1761-1769
In order to gain a better insight into the structure and function of the
regulatory domain (RD) of the cystic fibrosis transmembrane conductance
regulator (CFTR) protein, 19 RD missense mutations that had been identified
in patients were functionally characterized. Nine of these (I601F, L610S,
A613T, D614G, I618T, L619S, H620P, G628R and L633P) resulted in aberrant
processing. No or a very small number of functional CFTR proteins will
therefore appear at the cell membrane in cells expressing these mutants.
These mutations were clustered in the N- terminal part of the RD,
suggesting that this subdomain has a folding pattern that is very sensitive
to amino acid changes. Mutations that caused no aberrant processing were
further characterized at the electrophysiological level. First, they were
studied at the whole cell level in Xenopus laevis oocytes. Mutants that
induced a whole cell current that was significantly different from
wild-type CFTR were subsequently analysed at the single channel level in
COS1 cells transiently expressing the different mutant and wild-type
proteins. Three mutant chloride channels, G622D, R792G and E822K CFTR, were
characterized by significantly lower intrinsic chloride channel activities
compared with wild-type CFTR. Two mutations, H620Q and A800G, resulted in
increased intrinsic chloride transport activities. Finally, T665S and E826K
CFTR had single channel properties not significantly different from
wild-type CFTR.
相似文献
28.
Power spectral analysis of the electroencephalographic and hemodynamic correlates of propofol anesthesia in the rat: Intravenous infusion 总被引:2,自引:0,他引:2
Peter P. C. Tan Ming-Hwang Shyr Chen-Hsein Yang Terry B. J. Kuo Wynn H. T. Pan Samuel H. H. Chan 《Neuroscience letters》1993,160(2):205-208
Based on the tail-flick response to noxious thermal stimuli, we determined in the present study that effective antinociception could be achieved in adult male Sprague-Dawley rats 15 min after intravenous infusion of propofol at 60 mg/kg/h. Simultaneous power spectral analysis of the electroencephalographic (EEG) and systemic arterial pressure signals further revealed a concomitant depression of the activity of all EEG frequency bands (δ, θ, , β), alongside hypotension, negative inotropic and chronotropic actions, and attenuated baroreceptor reflex and vasomotor activity. These effects were congruent with a plasma concentration of propofol in the arterial blood of 1.70 ± 0.13 μg/ml, as determined by high-performance liquid chromatography. 相似文献
29.
30.
Cloning and expression of the gene involved in Sanfilippo B syndrome (mucopolysaccharidosis III B) 总被引:4,自引:1,他引:4
Sanfilippo B syndrome is caused by a deficiency of alpha-N-
acetylglucosaminidase, a lysosomal enzyme involved in the degradation of
heparan sulphate. Accumulation of the substrate in lysosomes results in
degeneration of the central nervous system with progressive dementia often
combined with hyperactivity and aggressive behaviour. In order to clone the
deficient gene, we purified the enzyme from human placenta and obtained
amino acid sequence information. Alignment of one of the CNBr generated
internal peptides to sequence from the database revealed the chromosomal
location of the gene in the 5' upstream flanking region of the gene for
17-beta-hydroxysteroid-dehydrogenase at 17q21.1. The available DNA sequence
was used to clone the cDNA coding for alpha-N- acetylglucosaminidase and
analyse its gene structure. The gene is fully contained in the 5' upstream
flanking region of the gene for 17-beta- hydroxysteroid-dehydrogenase and
interrupted by five introns. The cDNA clone has a length of 2575 bp and
encodes a protein of 743 amino acids. Chinese hamster ovary cells
transfected with the cDNA construct show alpha-N-acetylglucosaminidase
activity about 17-fold over background. This will allow correction studies
with NAG deficient Sanfilippo B cell lines and facilitate the development
of enzyme replacement therapy for these patients.
相似文献