全文获取类型
收费全文 | 6580篇 |
免费 | 485篇 |
国内免费 | 21篇 |
专业分类
耳鼻咽喉 | 125篇 |
儿科学 | 153篇 |
妇产科学 | 112篇 |
基础医学 | 947篇 |
口腔科学 | 65篇 |
临床医学 | 776篇 |
内科学 | 1539篇 |
皮肤病学 | 112篇 |
神经病学 | 502篇 |
特种医学 | 460篇 |
外国民族医学 | 9篇 |
外科学 | 720篇 |
综合类 | 103篇 |
一般理论 | 1篇 |
预防医学 | 351篇 |
眼科学 | 284篇 |
药学 | 341篇 |
1篇 | |
中国医学 | 14篇 |
肿瘤学 | 471篇 |
出版年
2022年 | 34篇 |
2021年 | 72篇 |
2020年 | 60篇 |
2019年 | 78篇 |
2018年 | 98篇 |
2017年 | 81篇 |
2016年 | 71篇 |
2015年 | 110篇 |
2014年 | 155篇 |
2013年 | 216篇 |
2012年 | 269篇 |
2011年 | 295篇 |
2010年 | 199篇 |
2009年 | 184篇 |
2008年 | 270篇 |
2007年 | 311篇 |
2006年 | 225篇 |
2005年 | 274篇 |
2004年 | 239篇 |
2003年 | 227篇 |
2002年 | 225篇 |
2001年 | 201篇 |
2000年 | 213篇 |
1999年 | 175篇 |
1998年 | 148篇 |
1997年 | 100篇 |
1996年 | 117篇 |
1995年 | 103篇 |
1994年 | 101篇 |
1993年 | 64篇 |
1992年 | 137篇 |
1991年 | 127篇 |
1990年 | 127篇 |
1989年 | 140篇 |
1988年 | 138篇 |
1987年 | 118篇 |
1986年 | 109篇 |
1985年 | 80篇 |
1984年 | 80篇 |
1983年 | 86篇 |
1982年 | 66篇 |
1981年 | 70篇 |
1980年 | 52篇 |
1979年 | 79篇 |
1978年 | 49篇 |
1977年 | 55篇 |
1976年 | 55篇 |
1975年 | 46篇 |
1974年 | 37篇 |
1973年 | 34篇 |
排序方式: 共有7086条查询结果,搜索用时 31 毫秒
61.
The occurrence, structure and innervation of slow and twitch muscle fibres in the tensor tympani and stapedius of the cat 总被引:2,自引:0,他引:2
1. The muscle fibres of the tensor tympani and stapedius of the cat have been examined in the light microscope in teased preparations after cholinesterase staining and in the electron microscope.2. In both muscles, two kinds of fibre have been found: those with an individual end-plate and those with multiple nerve terminals.3. The stapedius fibres with an end-plate have fibrils regularly separated from each other by sarcoplasmic reticulum, a straight Z line, transverse tubular T system elements regularly occurring at the junction of A and I bands, an M line, an extensive sole plate area, and numerous post-junctional sarcolemmal infoldings under the nerve terminal. This type of muscle fibre in the tensor tympani has all of these features except that the fibrils are not well separated from each other, T system elements are absent in some sarcomeres, and a typical M line is absent.4. Compared to the individually innervated fibres, the fibres with multiple endings have fibrils poorly separated from each other by sarcoplasmic reticulum, a jagged Z line, very few T system elements, a less extensive sole plate area, and essentially no folds under the nerve terminal. These fibres in both muscles have M lines.5. Muscle fibres have thus been found in both the tensor tympani and stapedius of the cat which conform in their innervation, the structure of their motor nerve endings, and their internal structure to many of the morphological characteristics which are exhibited by slow muscle fibres elsewhere. 相似文献
62.
K Matsuno T Schaffner H A Gerber C Ruchti M W Hess H Cottier 《Journal of the Reticuloendothelial Society》1983,33(4):263-273
The translocation of Percoll microspheres (mean diameter 20-30 nm) from the intestinal lumen through the epithelial layer to internal organs was examined in suckling mice using transmission electron microscopy. Repeated administration of this material by gavaging for 7 consecutive days resulted in a heavy particle load of vacuolated enterocytes. A limited amount of Percoll was transported to the subepithelial tissue of both the villous mucosa and Peyer's patches where microspheres were found endocytosed, predominantly by macrophages. Even smaller numbers of particles reached mesenteric lymph nodes and, occasionally, milky spots of the omentum. Minor Percoll aggregates were easily found in Kupffer cells of the liver, indicating hematogenous translocation. Small numbers of particles were regularly detected in perivascular macrophages of the thymic cortex, which are in close contact with surrounding lymphocytes. We conclude that the thymic cortex is not totally inaccessible to particulate matter of the intestinal content. 相似文献
63.
64.
Elastin point mutations cause an obstructive vascular disease, supravalvular aortic stenosis 总被引:7,自引:2,他引:7
Li DY; Toland AE; Boak BB; Atkinson DL; Ensing GJ; Morris CA; Keating MT 《Human molecular genetics》1997,6(7):1021-1028
Supravalvular aortic stenosis (SVAS) is an inherited obstructive vascular
disease that affects the aorta, carotid, coronary and pulmonary arteries.
Previous molecular genetic data have led to the hypothesis that SVAS
results from mutations in the elastin gene, ELN. In these studies, the
disease phenotype was linked to gross DNA rearrangements (35 and 85 kb
deletions and a translocation) in three SVAS families. However, gross
rearrangements of ELN have not been identified in most cases of autosomal
dominant SVAS. To define the spectrum of ELN mutations responsible for this
disorder, we refined the genomic structure of human ELN and used this
information in mutational analyses. ELN point mutations co-segregate with
the disease in four familial cases and are associated with SVAS in three
sporadic cases. Two of the mutations are nonsense, one is a single base
pair deletion and four are splice site mutations. In one sporadic case, the
mutation arose de novo. These data demonstrate that point mutations of ELN
cause autosomal dominant SVAS.
相似文献
65.
Neuronal Cell Death in Scrapie-Infected Mice Is Due to Apoptosis 总被引:3,自引:0,他引:3
Armin Giese Martin H. Groschup Barbara Hess Hans A. Kretzschmar 《Brain pathology (Zurich, Switzerland)》1995,5(3):213-221
Neuronal loss is a salient yet poorly understood feature in the pathology of transmissible spongiform encephalopathies (prion diseases). Cell culture experiments with neurotoxic prion protein fragments suggest that neuronal cell death in these diseases may be due to apoptosis. To test this hypothesis in vivo we used the in situ end-labeling (ISEL) technique and electron microscopy to study cell death in an experimental scrapie system in the mouse. ISEL, which relies on the incorporation of labeled nucleotides in fragmented DNA by terminal transferase, showed labeled nuclei in the brains and retinae of mice infected with the 79A strain of scrapie, whereas no labeling was observed in control animals. In the retina the highest numbers of labeled nuclei were found in the outer nuclear layer 120 days post infection followed by massive cell loss in this layer. In the brain, labeled nuclei were mainly found in the granular layer of the cerebellum of terminally ill mice. This corresponded to the presence of small dark nuclei with condensed and occasionally fragmented chromatin at the light and electron microscopical levels. Our results support the hypothesis that neuronal loss in spongiform encephalopathies is due to apoptosis. This may explain the almost complete absence of inflammatory response in prion diseases in the face of widespread neuronal cell death, and may also have therapeutic implications in the future. 相似文献
66.
N Chand F G Hess K Nolan W Diamantis J McGee R D Sofia 《International archives of allergy and applied immunology》1990,91(3):311-314
Guinea pigs were sensitized by intraperitoneal injection of ovalbumin, 10 micrograms mixed with 100 mg A1(OH)3 in saline. On days 15-30 sensitized guinea pigs were challenged with ovalbumin aerosol (0.5 mg/ml, 30 s, 15 psi) which produced immediate asthmatic responses characterized by dyspnea, convulsions, and some deaths during the first 14 min. Twenty to 24 h later the animals were sacrificed with an overdose of pentobarbital, and lungs, bronchi, and lower trachea were dissected and fixed in 10% neutral buffered formalin. Histopathological examination of randomly coded tissues of the respiratory tract revealed a pulmonary eosinophilic cellular infiltrate in the epithelium/subepithelium of trachea, bronchi, and bronchioles as well as the peribronchial, peribronchiolar, and perivascular areas of the lungs. Oral administration of mepyramine (10 mg/kg) 2 h before aeroallergen challenge provided complete protection against immediate asthmatic responses and prevented deaths during the first 14 min without influencing the late phase associated lung eosinophilic cellular infiltrate. The immediate asthmatic responses were not influenced by methylprednisolone (30 mg/kg) administered orally 24 and 2 h before aeroallergen challenge. Following an additional dose of methylprednisolone 4 h after challenge, there was a significant inhibition of pulmonary eosinophilia (30 mg/kg; -24 h, -2 h, and +4 h). These observations suggest that histamine is the principal mediator of immediate asthma attacks in guinea pigs. Methylprednisolone may be acting by inhibiting the production of eosinophil chemotactic factor of anaphylaxis (platelet-activating factor or leukotriene B4) from the alveolar macrophages, T lymphocytes, and perhaps other cells, thus preventing pulmonary eosinophilia. 相似文献
67.
68.
Zelinski-Wooten MB; Slayden OD; Chwalisz K; Hess DL; Brenner RM; Stouffer RL 《Human reproduction (Oxford, England)》1998,13(2):259-267
Large doses of antiprogestin typically disrupt menstrual cyclicity. A
chronic low-dose regimen of the potent new antiprogestin ZK 137 316, which
permits continued menstrual cyclicity but alters gonadal- reproductive
tract activity, was established. Rhesus monkeys received vehicle (n = 6) or
0.01 (n = 8), 0.03 (n = 8) or 0.1 (n = 5) mg ZK 137 316/kg body weight
daily for five menstrual cycles (C-1 to C-5). Oestradiol, progesterone and
gonadotrophin profiles were normal during cycles involving vehicle and 0.01
and 0.03 mg ZK 137 316/kg body weight. In the 0.1 mg/kg group, mid-cycle
oestradiol and gonadotrophin surges, and subsequent progesterone
production, were absent in C-3 and C-5. Ovarian cyclicity was accompanied
by timely menstruation in the vehicle and 0.01 mg/kg groups. By C-3, half
the animals in the 0.03 mg/kg group and all animals in the 0.1 mg/kg group
were amenorrhoeic. A corpus luteum was noted during the mid-luteal phase of
C-5 in the vehicle, 0.01 mg/kg and 0.03 mg/kg groups. Large antral and
cystic follicles were evident in the 0.1 mg/kg group. Thus, a daily
treatment with 0.01 mg/kg ZK 136317 permitted normal menstrual cyclicity in
macaques. While the daily administration of 0.03 mg/kg ZK 136 317 allowed
ovarian cyclicity, menstruation was disrupted in some animals. Increasing
the dose to 0.1 mg/kg antagonized pituitary function and resulted in
anovulation and amenorrhoea. A chronic low-dose regimen of the
antiprogestin ZK 137 316, which permits normal ovarian/menstrual cyclicity,
has potential as a contraceptive in women.
相似文献
69.
U Hess A Kappas G J McHugo J T Lanzetta R E Kleck 《International journal of psychophysiology》1992,12(3):251-265
Twenty-seven female undergraduates completed three tasks: (1) feel four emotions (happiness, sadness, anger, peacefulness); (2) express these emotions, without trying to feel them; and (3) feel and express clearly these four emotions. During each trial subjects pressed a button to indicate when they had reached the required state, and the latency from emotion cue to button press was measured. Heart rate, skin conductance and EMG from four facial sites (brow, cheek, jaw and mouth) were recorded for 15 s before and after the button press and during a baseline period prior to each trial. Self-reports were obtained after each trial. Facial EMG and patterns of autonomic arousal differentiated among the four emotions within each task. Shorter self-generation latency in the Feel-and-Show versus the Feel condition indicated the facilitative effect of facial expression on the self-generation of emotion. Furthermore, the presence of autonomic changes and self-reported affect in the Show condition supports the sufficiency version of the facial feedback hypothesis. The self-generation method employed as an emotion elicitor was shown to reliably induce emotional reactions and is proposed as a useful technique for the elicitation of various emotional states in the laboratory. 相似文献
70.
We used enzymatic digestion and mass spectrometry to identify the sites of glycosylation on the SU component of the Avian Sarcoma/Leukosis virus (ASLV) Envelope Glycoprotein (Subgroup A). The analysis was done with an SU(A)-rIgG fusion protein that binds the cognate receptor (Tva) specifically. PNGase F removed all the carbohydrate from the SU(A)-rIgG fusion. PNGase F is specific for N-linked carbohydrates; this shows that all the carbohydrate on SU(A) is N-linked. There are 10 modified aspargines in SU(A) (N17, N59, N80, N97, N117, N196, N230, N246, N254, and N330). All conform to the consensus site for N-linked glycosylation NXS/T. There is one potential glycosylation site (N236) that is not modified. Removing most of the carbohydrate from the mature SU(A)-rIgG by PNGase F treatment greatly reduces the ability of the protein to bind Tva, suggesting that carbohydrate may play a direct role in receptor binding. 相似文献