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   9761篇
  免费   854篇
  国内免费   44篇
耳鼻咽喉   116篇
儿科学   362篇
妇产科学   220篇
基础医学   1487篇
口腔科学   255篇
临床医学   838篇
内科学   2189篇
皮肤病学   265篇
神经病学   963篇
特种医学   432篇
外国民族医学   1篇
外科学   1327篇
综合类   53篇
一般理论   1篇
预防医学   717篇
眼科学   135篇
药学   628篇
中国医学   19篇
肿瘤学   651篇
  2023年   52篇
  2022年   117篇
  2021年   240篇
  2020年   155篇
  2019年   244篇
  2018年   312篇
  2017年   212篇
  2016年   237篇
  2015年   253篇
  2014年   308篇
  2013年   429篇
  2012年   542篇
  2011年   547篇
  2010年   355篇
  2009年   277篇
  2008年   433篇
  2007年   432篇
  2006年   462篇
  2005年   415篇
  2004年   378篇
  2003年   317篇
  2002年   326篇
  2001年   318篇
  2000年   304篇
  1999年   253篇
  1998年   127篇
  1997年   142篇
  1996年   125篇
  1995年   127篇
  1994年   87篇
  1993年   70篇
  1992年   210篇
  1991年   187篇
  1990年   168篇
  1989年   180篇
  1988年   173篇
  1987年   133篇
  1986年   129篇
  1985年   116篇
  1984年   98篇
  1983年   64篇
  1982年   45篇
  1981年   44篇
  1980年   38篇
  1979年   65篇
  1978年   40篇
  1977年   37篇
  1975年   34篇
  1974年   41篇
  1973年   34篇
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
31.
Digital dermatoglyphics of a sample from the Basque Valley of Salazar, situated in the West of the Pyrenees, were analysed. The results showed bimanual differences in both sexes, and also sexual differences for both hands. The comparative study with other Basque valleys showed that, in spite of their supposed common origin, the geographic barriers and the isolation have generated a genetic/dermatoglyphic and linguistic differentiation.  相似文献   
32.
We measured platelet-rich plasma (PRP) serotonin in patients suffering from tension-type headache, before and after treatment with amitriptyline, comparing them with a healthy control group and patients with untreated depression. We evaluated the severity of headache and depression in each group. PRP serotonin levels were higher in patients with headache than in controls and depressed patients. We observed a fall of PRP serotonin in patients with tension-type headache to similar levels after treatment as the depressed group. This fall was correlated with the improvement of headache but not with depression scales. Our data suggest that the rise of platelet serotonin levels in tension-type headache is related to pain and not depression.  相似文献   
33.
An attempt was made in two experiments to reinvestigate the effects of the antiandrogen cyproterone acetate (CA) on mouse social behavior in a variety of ethologically-assessed paired encounters. The data confirm that CA reduces offense (threat and attack) in animals when both subjects receive the material but that CA has no such action in other pairings. This suggests that CA's major suppressive effect on "hostility" is expressed in mice via a reduction in "attack-promoting" pheromone production. Indeed, there was evidence in the more chronic study that CA, could augment (via a central mechanism?) offense in subjects paired with docile anosmic opponents. Changes in defense were largely responses to variations in the degree of attack to which animals were subjected. The antihormone also had actions on other aspects of behavior including sexual activity, social investigation and immobility in such tests. CA had a potent suppressive action on the weights of sex accessory glands. The data do not suggest that CA can be used as a specific antihostility agent.  相似文献   
34.
Our experimental models in this study were cats fitted with gastric fistulae. Intravenous infusion of sulfated CCK 8 and nonsulfated Boc CCK 7 inhibited both sham-feeding and feeding in fasted cats. The threshold dose (1.2 pmol/kg.hr) required for inhibition of sham-feeding was identical to that required to inhibit feeding in the same animals. However, the gastric secretory studies indicated that this dose was 90 times lower than the threshold dose stimulating gastric acid secretion (109 pmol/kg.hr). In nonfasted animals, sulfated CCK 8 and nonsulfated Boc CCK 7 (219 and 875 pmol/kg.hr) are both capable of decreasing the food intake at different intervals following the infusion with no significant effect on daily food intake. Our findings clearly show that there is no difference in the sensitivity of CCK's ability to inhibit sham-feeding and feeding, suggesting that CCK's suppressive effect on food intake does not solely involve gastric distension mechanisms. In contrast to gastric acid secretion, the sulfate group is not a "restrictive" factor for peripherally-induced CCK satiety.  相似文献   
35.
36.
37.
A 22-year-old man with previous radiation treatment for childhood astrocytoma underwent resection of a right parietooccipital lesion. Histopathology revealed a malignant neoplasm with areas of astrocytic and primitive neuroectodermal components. To resolve the relationship and cellular origin, representative tissue was microdissected from several targets, obtaining a balanced mixture of each element. Nonneoplastic brain parenchyma was separately microdissected to determine polymorphic marker informativeness and to serve as an internal negative control. Despite the relatively small quantity of tissue removed for each microdissection target, sufficient material was available for reliable, balanced, polymerase chain reaction-format genotyping encompassing a panel of tumor suppressor genes and genetic loci associated with these forms of neoplasia. The findings revealed distinct discordant genotypic profiles for each of the neoplastic components. The efficacy of the approach used for molecular analysis of this complex neoplasm and the implication of the genotypic findings are discussed.  相似文献   
38.
Lysozyme was isolated from Bacillus Calmette-Guerin-elicited rabbit alveolar macrophages by acid extraction and purified to homogeneity by a single-column procedure. Yields of the purified enzyme averaged between 20 and 30 mg per rabbit, values far in excess of those obtained with previously published methods. Rabbit lysozyme has a molecular weight of 14,300 and exhibits optimal lytic activity against Micrococcus lysodeikticus at an ionic strength of 0.04, pH 6.5. Our results indicate that lysozyme and other granule components can be fractionated from elicited alveolar macrophages by using simple techniques, suggesting methods for the bulk purification of lysosomal constituents.  相似文献   
39.
The in vitro bactericidal reaction of human plasma serum against Bacillus subtilis was investigated. Human lysozyme was purified to homogeneity, and antiserum was prepared against the enzyme. The anti-lysozyme immunoglobulin G was used as a specific inhibitor in bactericidal and bacteriolytic reactions. It was found that at low serum concentrations lysozyme was the primary bactericide active against B. subtilis. At appreciably higher serum concentrations, a lysozyme-independent bactericidal activity was also demonstrated.  相似文献   
40.
Candida dubliniensis is an opportunistic yeast that has been increasingly implicated in oropharyngeal candidiasis (OPC) in human immunodeficiency virus (HIV)-infected patients but may be underreported due to its similarity with Candida albicans. Although most C. dubliniensis isolates are susceptible to fluconazole, the inducibility of azole resistance in vitro has been reported. Thus, the use of fluconazole prophylaxis in the treatment of these patients may have contributed to the increasing rates of isolation of C. dubliniensis. In this study, yeast strains were collected from the oral cavities of HIV-infected patients enrolled in a longitudinal study of OPC. Patients received fluconazole for the suppression or treatment of OPC, and isolates collected at both study entry and end of study were chosen for analysis. Samples were plated on CHROMagar Candida medium for initial isolation and further identified by Southern blot analysis with the species-specific probes Ca3 (for C. albicans) and Cd25 (for C. dubliniensis). Fluconazole MICs were determined by using NCCLS methods. At study entry, susceptible C. albicans isolates were recovered from oral samples in 42 patients who were followed longitudinally (1 to 36 months). C. albicans strains from 12 of these patients developed fluconazole resistance (fluconazole MIC, >/=64 micro g/ml). C. dubliniensis was not detected at end of study in any of these patients. Of the remaining 30 patients, eight (27%) demonstrated a replacement of C. albicans by C. dubliniensis when a comparison of isolates obtained at baseline and those from the last culture was done. For the 22 of these 30 patients in whom no switch in species was detected, the fluconazole MICs for initial and end-of-study C. albicans isolates ranged from 0.125 to 2.0 micro g/ml. For the eight patients in whom a switch to C. dubliniensis was detected, the fluconazole MICs for C. dubliniensis isolates at end of study ranged from 0.25 to 64 micro g/ml: the fluconazole MICs for isolates from six patients were 0.25 to 2.0 micro g/ml and those for the other two were 32 and 64 micro g/ml, respectively. In conclusion, a considerable number of patients initially infected with C. albicans strains that failed to develop fluconazole resistance demonstrated a switch to C. dubliniensis. C. dubliniensis in this setting may be underestimated due to lack of identification and may occur due to the impact of fluconazole on the ecology of oral yeast species.  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