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   4111篇
  免费   235篇
  国内免费   80篇
耳鼻咽喉   133篇
儿科学   93篇
妇产科学   22篇
基础医学   507篇
口腔科学   55篇
临床医学   345篇
内科学   994篇
皮肤病学   56篇
神经病学   145篇
特种医学   351篇
外科学   759篇
综合类   67篇
预防医学   185篇
眼科学   84篇
药学   387篇
中国医学   24篇
肿瘤学   219篇
  2023年   22篇
  2022年   49篇
  2021年   99篇
  2020年   42篇
  2019年   83篇
  2018年   102篇
  2017年   62篇
  2016年   78篇
  2015年   134篇
  2014年   161篇
  2013年   154篇
  2012年   284篇
  2011年   241篇
  2010年   152篇
  2009年   155篇
  2008年   226篇
  2007年   269篇
  2006年   212篇
  2005年   217篇
  2004年   174篇
  2003年   134篇
  2002年   107篇
  2001年   119篇
  2000年   84篇
  1999年   93篇
  1998年   77篇
  1997年   80篇
  1996年   75篇
  1995年   68篇
  1994年   55篇
  1993年   48篇
  1992年   38篇
  1991年   48篇
  1990年   49篇
  1989年   64篇
  1988年   50篇
  1987年   55篇
  1986年   27篇
  1985年   29篇
  1984年   18篇
  1983年   15篇
  1982年   21篇
  1981年   22篇
  1980年   25篇
  1979年   21篇
  1978年   13篇
  1977年   22篇
  1976年   17篇
  1975年   13篇
  1973年   4篇
排序方式: 共有4426条查询结果,搜索用时 15 毫秒
21.
The purpose of this study was to investigate the epidemiologic characteristics of the death by poisoning in Korea. We recoded the Death Certificates Database by injury based on the short version of the International Classification of External Causes of Injuries (ICECI). We evaluated the mortality rate by total injury and poisoning, and analyzed the mortality rate by age, gender, year and month, toxic agent, and intent. Adjusted odds ratios were calculated to evaluate the effects of socioeconomic factors on suicidal poisoning death. The total number of death cases by injury was 346,656. The proportion of death cases by injury decreased from 13.53% of all death cases in 1991 to 11.89% in 2001. However, the mortality rate by poisoning increased rapidly from 1998, and then remained stable. The number of suicidal poisoning deaths has gradually increased, and its mortality rate was 6.41 (per 100,000) in 2001. Major toxic agents were pesticides and herbicides (50.90%) in 2001. Adjusted odds ratios of suicidal poisoning versus other poisonings showed significant differences in education attainment, region, and marital status. In conclusion, the mortality rate by poisoning has increased, and the proportion of suicidal poisoning also has increased compared to that of accidental poisoning.  相似文献   
22.
We have treated a total of 16 cases of advanced Kienböck''s disease, stage III and IV by Lichtman''s classification, with triscaphe fusion, tendon ball replacement arthroplasty after excision of lunate, proximal row carpectomy as a salvage procedure and limited wrist fusion, since 1985. All cases were followed for minimal 16 months after each operation. Tendon ball replacement arthroplasty after excision of lunate could not prevent further carpal collapse with persistent chronic wrist pain. The triscaphe fusion or radio-lunate fusion induced a marked limited wrist motion later, and the triscaphe fusion alone was not fit for the treatment of advanced one because of progressive proximal migration of capitate and continuous wrist pain due to ligamentous carpal instability in follow-up. So we tried to simultaneously combine tendon ball replacement arthroplasty after excision of lunate with triscaphe fusion in far advanced Kienböck''s disease, and their end results was favorable. Proximal row carpectomy could be done in far advanced Kienböck''s disease with reasonably painless wrist motions. The overall end results of proximal row carpectomy are much better than any form of carpal arthrodesis. Conclusively the proper way to treat advanced Kienböck''s disease seems to depend on the patient''s age, their job and sex, and the stage of disease. And the cause of wrist pain in advanced Kienböck''s disease seems due to ligamentous carpal instability rather than osteoarthritis on radio-lunate joint.  相似文献   
23.
24.
25.
The predominant enzymes responsible for elimination of hydrogen peroxide (H(2)O(2)) in cells are peroxiredoxins (Prxs), catalase, and glutathione peroxidases (GPxs). Evidence suggests that catalytic activities of certain isoforms of these H(2)O(2)-eliminating enzymes are extensively regulated via posttranslational modification. Prx I and Prx II become inactivated when phosphorylated on Thr(90) by cyclin B-dependent kinase Cdc2. In addition, the active-site cysteine of Prx I-IV undergoes a reversible sulfinylation (oxidation to cysteine sulfinic acid) in cells. Desulfinylation (reduction to cysteine) is achieved by a novel enzyme named sulfiredoxin. c-Abl and Arg nonreceptor protein tyrosine kinases associate with catalase in cells treated with H(2)O(2) by mechanisms involving the SH3 domains of the kinases and the Pro(293)PheAsnPro motif of catalase and activate catalase by phosphorylating it on Tyr(231) and Tyr(386). Similarily, GPx1 is activated by c-Abl- and Arg-mediated phosphorylation. The tyrosine phosphorylation is critical for ubiquitination-dependent degradation of catalase.  相似文献   
26.
We explore the pursuit in a plane of a target moving at constant slow speed in a straight line. Two models of the pursuit are given. In the continuous case, the pursuer is moving at constant speed and is subject to proportionate angular homeostasis with correction constant b. In the discrete version movement occurs at a constant speed in a sequence of straight line segments of constant length (called the step size, s) the end of the segments being called the vertices. The pattern considered is not the absolute position of the pursuer, but its distance and orientation relative to the target. Both the transients and the asymptotic orbit are addressed. A key quantity is r, the speed of the target expressed as a fraction of that of the pursuer. If the speed of the pursuer is defined as unity, r is also the ratio of the speeds. There exists a critical speed fraction, R(b,s), a function of b and s, that defines what the term slow designates. R(b,s), which has to be found numerically, has the following property. For r less than R(b,s), the asymptotic path is a simple closed curve. In the discrete case the vertices converge to a simple closed curve. The larger r, the more the path (or in the discrete analogue its set of vertices) departs from a circle, and the more eccentric the target is with respect to it. Interest centers on two issues. First we address the transient patterns of the path, notably whether or not the sense of any particular path (clockwise or counterclockwise) is the same throughout, or changes at some stage.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
27.
28.
The effect of membrane stretch on voltage-activated Ba2+ current (I Ba) was studied in antral circular myocytes of guinea-pig using the whole- cell patch-clamp technique. The changes in cell volume were elicited by superfusing the myocytes with anisosmotic solutions. Hyposmotic superfusate (202 mosmol/l) induced cell swelling and increased peak values of I Ba at 0 mV (from −406.6 ± 45.5 pA to −547.5 ± 65.6 pA, mean ± SEM, n = 8) and hyperosmotic superfusate (350 mosmol/l) induced cell shrinkage and decreased peak values of I Ba at 0 mV (to −269.5 ± 39.1 pA, n = 8). Such changes were reversible and the extent of change was dependent on the osmolarity of superfusate. The values of normalized I Ba at 0 mV were 1.43 ± 0.04, 1.30 ± 0.06, 1.23 ± 0.04, 1.19 ± 0.04, 1 and 0.68 ± 0.06 at 202, 220, 245, 267, 290 and 350 mosmol/l, respectively (n = 8). I Ba was almost completely blocked by nicardipine (5 μM) under hyposmotic conditions. The values of steady-state half-inactivation voltage (−37.7 ± 3.3 and −36.5 ± 2.6 mV, under control and hyposmotic conditions, respectively) or the half-activation voltage (−13.6 ± 2.3 and −13.9 ± 1.9 mV) of I Ba were not significantly changed (P > 0.05, n = 6). Cell membrane capacitance was slightly increased from 50.00 ± 2.86 pF to 50.22 ± 2.82 pF by a hyposmotic superfusate (P < 0.05, n = 6). It is suggested that cell swelling increases voltage-operated L-type calcium channel current and that such a property is related to the response of gastric smooth muscle to mechanical stimuli. Received: 14 November 1995/Received after revision and accepted: 8 January 1996  相似文献   
29.
Neurofibromatosis 2 (NF2) is an inherited cancer syndrome resulting from mutations in the NF2 tumor suppressor gene. Analysis of NF2 mutations has revealed some general genotype-phenotype correlations. Severe disease has been associated with mutations that produce a premature termination while more mild disease has been associated with missense mutations. Here, we provide experimental proof for these genotype-phenotype correlations by demonstrating that nonsense mutations fail to produce stable merlin protein while missense mutations result in the generation of merlin proteins defective in negative growth regulation. This inability to suppress cell growth may result from defects in the function of merlin at several levels, including failure to form an intramolecular complex. Based on these findings, we propose a model for merlin growth suppression that provides a framework for analyzing NF2 patient mutations and merlin function.   相似文献   
30.
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