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   37500篇
  免费   3804篇
  国内免费   69篇
耳鼻咽喉   480篇
儿科学   1021篇
妇产科学   759篇
基础医学   5280篇
口腔科学   1379篇
临床医学   4284篇
内科学   7609篇
皮肤病学   629篇
神经病学   2964篇
特种医学   1340篇
外国民族医学   2篇
外科学   4887篇
综合类   933篇
一般理论   30篇
预防医学   3971篇
眼科学   1004篇
药学   2844篇
  1篇
中国医学   27篇
肿瘤学   1929篇
  2021年   527篇
  2020年   331篇
  2019年   555篇
  2018年   607篇
  2017年   454篇
  2016年   498篇
  2015年   606篇
  2014年   836篇
  2013年   1262篇
  2012年   1673篇
  2011年   1770篇
  2010年   966篇
  2009年   966篇
  2008年   1554篇
  2007年   1656篇
  2006年   1529篇
  2005年   1586篇
  2004年   1443篇
  2003年   1387篇
  2002年   1364篇
  2001年   1099篇
  2000年   1171篇
  1999年   1103篇
  1998年   444篇
  1997年   362篇
  1996年   413篇
  1995年   379篇
  1994年   382篇
  1993年   363篇
  1992年   910篇
  1991年   850篇
  1990年   902篇
  1989年   812篇
  1988年   781篇
  1987年   764篇
  1986年   715篇
  1985年   714篇
  1984年   559篇
  1983年   499篇
  1982年   320篇
  1981年   335篇
  1980年   301篇
  1979年   471篇
  1978年   387篇
  1977年   309篇
  1976年   294篇
  1974年   376篇
  1973年   370篇
  1972年   304篇
  1971年   320篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Elevated levels of acute phase plasma proteins in major depression.   总被引:10,自引:0,他引:10  
Levels of acute phase and other plasma proteins were measured in 21 men with major depression, 28 men with alcohol dependence, and 12 men who acted as controls. The depressed men had significantly elevated levels of the acute phase proteins, haptoglobin and alpha-1-antichymotrypsin, and of immunoglobulin G. The elevations in haptoglobin and alpha-1-antichymotrypsin were highly correlated with each other, and were correlated with the severity of depression and negatively correlated with the thyroid stimulating hormone response to thyrotropin. The alcoholic men had elevated haptoglobin levels, but significantly decreased levels of immunoglobulin G. These findings provide further evidence for an inflammatory response during depression.  相似文献   
82.
合成了18个O,O′-二烷基-O″-(5-取代-3-苯并噻吩乙腈肟)磷酸酯及硫代磷酸酯类化合物(Ⅰ1~18)。初步杀螺试验结果表明,其中5个化合物,即Ⅰ2,3,7,11,12有明显的杀螺增效作用。  相似文献   
83.
Primary dystonia is a disorder of movement for which no consistent pathophysiology has been identified; in the absence of evidence to the contrary, it is assumed to be cognitively benign. We have studied a clinically heterogeneous group of 14 patients with primary dystonia on a battery of neuropsychological tests. Despite well-preserved speed of information processing, language, spatial, memory and general intellectual skills relative to normal controls, we have identified a constellation of attentional-executive cognitive deficits on the Cambridge Neuropsychological Test Automated Battery (CANTAB). Specifically, patients demonstrated significant difficulties negotiating the extra-dimensional set-shifting phase of the IED task. The implications of these findings for the pathophysiology of primary dystonia are discussed. This is, to the best of our knowledge, the first report of a significant cognitive deficit in patients with primary dystonia.  相似文献   
84.
We report the clinical and operative details of seven cases of fracture of the femoral stem of the Ring TiMESH cementless hip prosthesis (two were cemented and five uncemented). Six fractures occurred in the proximal one-third of the stem and one at mid-stem. The failures are attributed mainly to two defects in stem design, the narrowness of the anteroposterior dimensions and the depth of the recess for the titanium mesh pads. Great difficulty was experienced in removing the osseo-integrated distal fragments of the broken stems.  相似文献   
85.
OBJECTIVES: To investigate the etiology of nasal polyps and its relationship to allergy. The prevalence of positive food and inhalant skin tests in patients with nasal polyps and nonatopic controls was compared. STUDY DESIGN AND SETTING: Prospective controlled study in tertiary referral rhinology clinic. RESULTS: Seventy percent (70%) of the patients with nasal polyps had positive skin tests to an average of four foodstuffs, compared to 34 percent of controls (P = 0.006). Only 35 percent of the nasal polyp patients also had positive inhalant skin tests. Overall, the prevalence of positive inhalant skin tests was similar in the nasal polyp patients and controls. CONCLUSIONS: These findings suggest that the positive skin tests to foods are not merely a reflection of the general atopic status of patients with nasal polyps. It may be that non-IgE-mediated hypersensitivities, such as to ingested foods, play a role on the basis of a significant number of patients with positive intradermal skin tests to foods. SIGNIFICANCE: Evaluation of the allergic status of patients with polyposis is important. Dietary manipulation may be indicated, though its role needs further investigation.  相似文献   
86.
A 4-year, 9-month-old boy had a history of leukocoria of the right eye for approximately six months prior to admission. The other eye was normal. There was no family history of retinoblastoma. Funduscopy disclosed a large white mass extending from the nasal pars plana to the mid-pupillary zone and the posterior pole with a near total retinal detachment in the superior temporal quadrant. A B-scan ultrasound showed an echo dense area of the anterior portion of the mass. A CT scan showed intraocular tissue densities with no evidence of optic nerve involvement or extraocular extension. Immunohistochemistry of a fresh frozen portion of tumor revealed reactivity with antibodies directed against interphotoreceptor retinoid-binding-protein (IRBP), neuron-specific enolase, glial fibrillary acidic protein, S-antigen, focal reactivity with opsin, and scattered cytoplasmic staining for cyclic GMP and cyclic GMP phosphodiesterase. Biochemical analysis of fresh frozen tissue samples confirmed the presence of IRBP. Transmission electron microscopy disclosed occasional Flexner-Wintersteiner rosettes connected by zonula adherens-like junctions. These showed inner segment-like structures containing prominent mitochondria, portions of cilia and fragments of outer segment material. These data, along with the immunocytochemistry indicates a predominant neuronal nature of the tumor cells with significant photoreceptor-like differentiation.  相似文献   
87.
The possibility that injection-molded intraocular lenses (IOLs) with imperfections called iridescent clefts could have a decreased threshold to neodymium: YAG (Nd:YAG) laser-induced damage was investigated. Thresholds for Nd:YAG laser-induced damage were determined for injection-molded and lathe-cut polymethylmethacrylate lenses. When aimed at a membrane in contact with a posterior convex surface, the average thresholds were 0.96 +/- 0.18 mJ (Standard deviation [SD]) and 1.80 +/- 0.55 mJ, respectively. The difference was significant at P = 0.001. When injection-molding polymethylmethacrylate was used to make lathe-cut IOLs, very few iridescent clefts were present, and the threshold to Nd:YAG laser-induced damage was 0.94 +/- 0.25 mJ. Iridescent clefts are therefore produced during the injection-molding process but they do not lower the threshold to Nd:YAG laser-induced damage. Rather, the reduced threshold in injection-molded lenses is most probably a result of the polymethylmethacrylate used in their manufacture. Clinically, iridescent clefts in a lens suggest that it has been manufactured by an injection-molding process and that Nd:YAG laser posterior capsulotomy must be performed at the lowest possible energy level to avoid damage.  相似文献   
88.
89.
A well-nourished alcoholic patient developed a subacute myopathy which responded rapidly to correction of severe hypomagnesaemia. The finding of profound hypocalcaemia prompted the measurement of serum magnesium. Magnesium deficiency should be looked for in any alcoholic patient with a myopathy as the prognosis seems better than in many other forms of alcoholic myopathy. Correction of the magnesium deficiency corrects the hypocalcaemia without the need for calcium supplementation.  相似文献   
90.
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