首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   324207篇
  免费   29099篇
  国内免费   22881篇
耳鼻咽喉   2989篇
儿科学   3422篇
妇产科学   4925篇
基础医学   39954篇
口腔科学   5495篇
临床医学   45264篇
内科学   49704篇
皮肤病学   3082篇
神经病学   18365篇
特种医学   11979篇
外国民族医学   213篇
外科学   33218篇
综合类   49861篇
现状与发展   76篇
一般理论   20篇
预防医学   19616篇
眼科学   9573篇
药学   32794篇
  334篇
中国医学   17434篇
肿瘤学   27869篇
  2024年   1003篇
  2023年   5014篇
  2022年   13046篇
  2021年   16394篇
  2020年   12040篇
  2019年   10894篇
  2018年   11412篇
  2017年   9917篇
  2016年   9362篇
  2015年   14355篇
  2014年   17800篇
  2013年   15345篇
  2012年   22800篇
  2011年   25807篇
  2010年   15904篇
  2009年   12248篇
  2008年   17013篇
  2007年   17016篇
  2006年   17049篇
  2005年   16773篇
  2004年   10663篇
  2003年   9762篇
  2002年   8439篇
  2001年   7467篇
  2000年   8277篇
  1999年   9018篇
  1998年   5475篇
  1997年   5499篇
  1996年   4332篇
  1995年   3922篇
  1994年   3213篇
  1993年   2097篇
  1992年   2827篇
  1991年   2415篇
  1990年   2117篇
  1989年   1861篇
  1988年   1563篇
  1987年   1352篇
  1986年   1107篇
  1985年   913篇
  1984年   526篇
  1983年   373篇
  1982年   242篇
  1981年   238篇
  1980年   188篇
  1979年   221篇
  1978年   82篇
  1977年   89篇
  1974年   102篇
  1973年   83篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
BACKGROUND AND PURPOSE: Health-related quality of life (HRQOL) is primarily an assessment of how domains of life are affected by health. This study investigated the factors influencing HRQOL of Taiwanese patients with bronchial asthma. METHODS: A cross-sectional study was conducted to assess the factors influencing HRQOL. The sample consisted of 242 outpatients with bronchial asthma. The Chinese language version of the St. George's Respiratory Questionnaire was used to measure HRQOL. Data were analyzed using simple regression and multiple regression. RESULTS: Age, marital status, level of education, asthma severity, peak expiratory flow, and previous hospital admissions were found to be predictors of HRQOL. Gender, duration of disease, and history of emergency visits were not correlated with HRQOL. The variables entered in the HRQOL model accounted for 17.4% of the total variance (adjusted R(2)). The regression coefficients indicated that the mean scores increased 7.68 in patients with moderate to severe disease severity, and increased 7.34 in patients with a history of hospital admissions. The mean scores decreased 7.60 in married patients. CONCLUSION: This study found that marital status, asthma severity, and history of hospital admissions were major predictors of HRQOL in Taiwanese patients with bronchial asthma.  相似文献   
72.
As an ongoing effort to elucidate the mechanisms involved in the calcium-dependent fertility regulation process, the viscoelastic properties of the mucus obtained from lamb cervix and human semen, as well as their water and total protein contents after exposure to EDTA, a chelating agent, or Nonoxynol-9 (N-9), a spermicidal agent, were examined. The viscosity was measured using a Cone Plate Digital Viscometer, while the water and total protein contents were determined by the lyophilization process and the Lowry method, respectively. The significant changes in the rheological properties of mucus, such as its viscosity and the water content, upon exposure to EDTA were demonstrated. The viscosity of cervical mucus and human semen were significantly increased by EDTA treatment (as compared to the controls): lamb cervical mucus (2.9 ± 0.3 vs. 2.2 ± 0.3 cps) and human semen (5.0 ± 0.3 vs. 4.3 ± 0.3 cps), respectively. The hydration rate was decreased by EDTA treatment as compared with the control (93.6 ± 0.7 vs. 96.8 ± 0.8%). Among tested samples, the reduction in the percentage of sperm penetration through the cervical mucus was the highest in the mucus containing EDTA, which had the lowest water content (93.6 ± 0.7%), indicating that there is a positive relationship between the hydration rate of the cervical mucus and its ability to permit the penetration of spermatozoa. This result indicates that spermicidal activity exerted by high concentrations of EDTA is in part due to its effect on the rheological properties of cervical mucus or semen.  相似文献   
73.
Since the beginning of this century, trans- naso-sphenoidal resection of the pituitary fossa tumors has been widely used clinically. It has more merits than other operative approaches used before. In China it has been adopted by both ENT doctors and neurosurgeons since 1959.1 In order to afford some relevant anatomical data, we measured 137 adult sagittal plane skulls with distinct landmarks.  相似文献   
74.
OBJECTIVE: To examine the distribution of rat facial motoneurons contributing different branches under normal situation and when nerve reinnervation occurred following facial nerve axotomy. METHODS: The normal distribution of motoneurons innervated both buccal and marginal mandibular branches and its reorganization after facial nerve reinnervation was observed using retrograde labeling with fluorescein. RESULTS: Under normal situation, the motoneurons contributing buccall and marginal mandibular branches were primarily distributed in the intermedial and lateral subnucleus in facial nucleus and almost completely overlapped. The two types labeled neurons organized closely, but there were no double-labeled neurons. Although the motoneurons contributing buccall and marginal mandibular branches were primarily overlapped 4 month post-anastomosis, the number of the labeled neurons obviously decreased and the organization got more scattered. There were 10% of buccall branches, 5% of marginal mandibular motoneurons in the dorsal subnuleus, 1% of buccall and 4% of marginal mandibular in dorsal ventral and medial subnucleus. The distribution pattern of the motoneurons 6 month post-anastomosis was similar to that of 4 month post-anastomosis, but the number of the labeled neurons increased, and there were 1%-2% double-labeled neurons. CONCLUSION: The distribution pattern of motoneurons innervated both buccal and marginal mandibular branches indicates that it should exist wide-spread communicating branches, and its reorganization after facial nerve reinnervation suggests that misdirected regeneration occurs among motoneurons innervating different branches.  相似文献   
75.
76.
77.
The effect of lowered estradiol levels on periodontal tissue   总被引:1,自引:0,他引:1  
  相似文献   
78.
The firing rate of locus coeruleus (LC) neurons in rat brain slices was increased reversibly by agents that either elevate intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) or mimic its actions (e.g., forskolin, and activator of adenylate cyclase, 8-Br-cAMP, a membrane permeable analog of cAMP, and Ro20-1724, a preferential inhibitor of cAMP-phosphodiesterase). Intracellular recordings showed that 8-Br-cAMP and forskolin induce a depolarization of LC neurons, accompanied by a decrease in input resistance. The 8-Br-cAMP- and forskolin-elicited depolarization persisted in the presence of cobalt, a calcium channel blocker. Steady-state current-voltage curves revealed that in the voltage range of -50 to -120 mV, 8-Br-cAMP and forskolin induced an inward current, which did not reverse at the potassium equilibrium potential and could not be blocked by tetrodotoxin. Partial replacement of sodium with Tris or choline markedly reduced the depolarization elicited by 8-Br-cAMP. We conclude that 8-Br-cAMP and forskolin act through a common mechanism to increase the firing rate of locus coeruleus neurons by inducing a cAMP-activated inward current, carried out at least in part by sodium ions.  相似文献   
79.
The depolarization of frog sciatic nerves by the Na channel-activating toxins, batrachotoxin and veratridine, was studied using the sucrose-gap technique. To study the interaction between the activators and the gating processes of Na channels, we measured the depolarizations of unstimulated nerves, of nerves during repetitive stimulation, and of nerves whose Na channel inactivation process had been pharmacologically modified. Stimulation enhanced the rates of depolarization by the activators but did not effect the steady state depolarization values. Of the three inhibitors of Na channel inactivation that were tested (Leiurus alpha-scorpion toxin, chloramine T, and Ni2+), only Leiurus toxin enhanced the potencies of the activators. Neither chloramine T nor Ni2+ had any effect on the steady state level of depolarization produced by either activator. Both chloramine T and Ni2+, however, enhanced the rate of batrachotoxin action, although neither affected the rate of veratridine action. Leiurus toxin also potentiated the effects of the activators in chloramine T-treated nerves. We tested the interaction between the Na channel activators and a class of agents, local anesthetics, that stabilize a non-conducting state of the Na channel. The presence of lidocaine inhibited the depolarization produced by addition of either activator, although the addition of lidocaine subsequent to the development of batrachotoxin-induced depolarization produced repolarization very weakly and slowly. We also found that the lidocaine homologue, RAC 109I, was about 3 times as potent as its stereoisomer, RAC 109II, in its ability both to reduce the compound action potential amplitude and to inhibit the veratridine-induced depolarization.  相似文献   
80.
提壶揭盖法治疗前列腺增生症82例   总被引:5,自引:0,他引:5  
笔者自1995年以来,宗提壶揭盖法,用补中益气汤加减治疗前列腺增生82例疗效满意,报告如下。  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号