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   9204篇
  免费   935篇
  国内免费   25篇
耳鼻咽喉   61篇
儿科学   327篇
妇产科学   186篇
基础医学   1194篇
口腔科学   141篇
临床医学   1009篇
内科学   1960篇
皮肤病学   68篇
神经病学   753篇
特种医学   446篇
外国民族医学   5篇
外科学   1229篇
综合类   268篇
现状与发展   1篇
一般理论   15篇
预防医学   1061篇
眼科学   223篇
药学   837篇
  1篇
中国医学   2篇
肿瘤学   377篇
  2021年   138篇
  2020年   88篇
  2019年   157篇
  2018年   165篇
  2017年   134篇
  2016年   145篇
  2015年   156篇
  2014年   222篇
  2013年   309篇
  2012年   456篇
  2011年   482篇
  2010年   237篇
  2009年   227篇
  2008年   447篇
  2007年   493篇
  2006年   448篇
  2005年   463篇
  2004年   448篇
  2003年   375篇
  2002年   376篇
  2001年   280篇
  2000年   282篇
  1999年   225篇
  1998年   118篇
  1997年   132篇
  1996年   121篇
  1995年   77篇
  1994年   93篇
  1993年   88篇
  1992年   175篇
  1991年   170篇
  1990年   157篇
  1989年   152篇
  1988年   132篇
  1987年   149篇
  1986年   115篇
  1985年   126篇
  1984年   98篇
  1983年   103篇
  1982年   88篇
  1981年   70篇
  1980年   72篇
  1979年   121篇
  1978年   71篇
  1977年   74篇
  1976年   59篇
  1974年   64篇
  1973年   62篇
  1972年   57篇
  1968年   64篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Many studies have been published which have examined the relationship between paid employment and women's health. As employment outside the home is likely to have differential effects for women with different family commitments, further analysis taking account of the association between paid employment and household circumstances is necessary. Using data from a large, representative British sample, this paper examines the effects of interactions between paid employment, social class, and parental status on women's health. The results show differential effects of these variables on physical and mental health. The most important influence on women's mental health (as measured by the 30-item General Health Questionnaire) is the age of their youngest child; women with children under five are most likely to show signs of psychological disturbance. With respect to physical health, age of the youngest child has no significant effect, but there is an interaction between employment status and social class. Paid employment, particularly full-time work, is associated with good physical health for middle-class women but not for working-class women.  相似文献   
92.
(1) The effects of benzocaine on the ionic currents in the voltage-clamped squid giant axon have been examined under various conditions; intact axons internally perfused with CsF and axons dialysed with tetraethyl-ammonium ions were used. (2) Both the steady state outward (potassium) current and the early transient (sodium) current were reduced by ca. 50% by benzocaine (1 mM). (3) Plots of the changes produced by benzocaine (1 mM) in the Hodgkin-Huxley parameters for the steady state activation (m), the steady state inactivation (h) and the time constants (m and h) for activation and inactivation of the sodium current are shown. Them andh curves are shifted in positive and negative directions respectively on the voltage axis. The time constants are not greatly affected. (4) In axons in which the sodium current inactivation had been largely removed by treatment with chloramine T, the sodium current was still reduced by ca. 50% by 1 mM benzocaine and the positive shift in activation remained unchanged. (5) The dependence on benzocaine concentration (for2mM) of the peak sodium current reduction and the shift in steady state inactivation have been determined. (6) It is concluded that in the squid axon the effects on inactivation are not the main reason for the reduction of the sodium current by benzocaine and that, in common with many other neutral anaesthetics, there are at least two sites at which benzocaine acts.  相似文献   
93.
When virulent Legionella pneumophila is passaged on supplemented Mueller-Hinton agar, it remains virulent for guinea pigs and embryonated hen eggs for two passages. However, by the fifth passage the cultures become avirulent for guinea pigs. Flagella were not produced by L. pneumophila on the first passage on supplemented Mueller-Hinton agar. In contrast, 12 passages on charcoal-yeast extract agar did not result in the reduction of virulence or the loss of flagella of L. pneumophila. Growth in supplemented yeast extract broth or on Norit-A-filtered supplemented yeast extract agar also did not result in a reduction of the virulence of L. pneumophila. However, L. pneumophila did not produce flagella when grown on these two media. Thus, it appears that the production of flagella is not required for the virulence of L. pneumophila when administered by the intraperitoneal route of infection. A virulent flagellated form of L. pneumophila was recovered by passing an avirulent form six times in guinea pigs. When avirulent L. pneumophila was passaged 12 times in embryonated eggs, a nonflagellated form of the bacterium was recovered which had an increased virulence for guinea pigs and embryonated eggs. However, virulent forms were not recovered by passage of avirulent forms on commonly used laboratory media. These results support the suggestion that a suitable host is required for the selection of the virulent form of L. pneumophila from avirulent cultures.  相似文献   
94.
T-lymphocyte-adherent mononuclear cell interaction was analyzed in the vigorous and immunomodulated liver granulomas of Schistosoma mansoni-infected mice. Collagenase-dispersed granulomas contained 15% lymphocytes, 30% macrophages, 50% eosinophilis, and some neutrophils. Dispersed granuloma cells stimulated with concanavalin A or soluble worm egg antigens (SEA) did not proliferate unless plate-adherent, esterase-positive mononuclear cells were removed before culture. To analyze the granuloma adherent cell-mediated suppression, vigorous granuloma cell cultures partially depleted of adherent mononuclear cells were supplemented with indomethacin, catalase, superoxide dismutase, levamisole, and anti-murine alpha/beta interferon antiserum. In concanavalin A and SEA-stimulated cultures, only the addition of indomethacin or anti-alpha/beta interferon antiserum alleviated the adherent cell-mediated suppression of vigorous granuloma lymphocyte response. In contrast, these agents only minimally alleviated the suppressed response of SEA-stimulated, immunomodulated granuloma lymphocytes. Moreover, coculture of equal numbers of vigorous and immunomodulated granuloma cells partially depleted of adherent suppressor cells abrogated the alleviated response of vigorous granuloma lymphocytes. These findings indicate that, within the schistosome egg-induced vigorous granulomas, the adherent mononuclear cells exert regulation over lymphocyte responsiveness by alpha/beta-interferon and an indomethacin-sensitive, probably prostaglandin-mediated pathway. Within the immunomodulated granulomas, the adherent suppressor cell-mediated regulation of lymphocyte proliferation appears to play a lesser role.  相似文献   
95.
Summary Invertebrate mini-titins are members of a class of myosin-binding proteins belonging to the immunoglobulin superfamily that may have structural and/or regulatory properties. We have isolated mini-titins from three molluscan sources: the striated and smooth adductor muscles of the scallop, and the smooth catch muscles of the mussel. Electron microscopy reveals flexible rod-like molecules about 0.2 m long and 30 Å wide with a distinctive polarity. Antibodies to scallop mini-titin label the A-band and especially the A/I junction of scallop striated muscle myofibrils by indirect immunofluorescence and immuno-electron microscopy. This antibody crossreacts with mini-titins in scallop smooth and Mytilus catch muscles, as well as with proteins in striated muscles from Limulus, Lethocerus (asynchronous flight muscle), and crayfish. It labels the A/I junction (I-region in Lethocerus) in these striated muscles as well as in chicken skeletal muscle. Antibodies to the repetitive immunoglobulin-like regions and also to the kinase domain of nematode twitchin crossreact with scallop mini-titin and label the A-band of scallop myofibrils. Electron microscopy of single molecules shows that antibodies to twitchin kinase bind to scallop mini-titin near one end of the molecule, suggesting how the scallop structure might be aligned with the sequence of nematode twitchin.  相似文献   
96.
We have shown that immunization of non-obese diabetic (NOD) mice with adjuvants (CFA or BCG) prevents the onset of diabetes by induction of regulatory cells. Since autoimmune responses to glutamic acid decarboxylase (GAD) are up-regulated in insulin-dependent diabetes mellitus (IDDM), in this study GAD67-specific antibody, T cell proliferation and lymphokine production patterns were analysed in the adjuvant-treated mice to characterize the regulatory mechanisms underlying the protection. We used both spontaneous diabetes and syngeneic islet transplantation models in NOD mice. Protection against spontaneous diabetes and prevention of syngeneic islet graft rejection by CFA or BCG treatment was found to be accompanied by the production of long lasting and high titre anti-GAD67 antibody of IgG1 isotype in the sera. Uponin vitrostimulation with GAD67, draining lymph node and spleen cells from CFA-immunized NOD mice or syngeneic islet-grafted and BCG-protected NOD mice produced much more IL-4, whereas there was no significant change in IFN-γ production. The strong early T cell proliferative response to GAD67 in CFA or BCG-immunized NOD mice was followed by a low or unresponsiveness state. Taken together, these results suggest a shift in Th1/Th2 balance in the GAD67-specific endogenous immune response to a change in Th2 levels after adjuvant treatment. We postulate that the protective effect of CFA or BCG is due to the diversion of GAD-specific endogenous cellular immune response to a non-pathogenic humoral response.  相似文献   
97.
We compared outer membrane protein (OMP) patterns of Haemophilus influenzae isolated in metropolitan Atlanta, Ga., from July 1983 to June 1985. Of 74 randomly selected H. influenzae serotype b, biotype I, isolates (24% of the total number of H. influenzae, and 32% of the total number of H. influenzae serotype b, biotype I, isolates), 66 (89.2%) had the same OMP pattern. Of the remaining eight, five (6.7%) had an identical OMP pattern. The other three isolates had separate and distinct patterns. A greater diversity of OMP patterns was found with H. influenzae serotype b, biotype II, and nonserotypeable H. influenzae. Of the 18 H. influenzae serotype b, biotype II, isolates (5.8% of the total number of H. influenzae isolates), 1 had an OMP pattern similar to that of the predominate biotype I OMP type, 6 (33% of the biotype II) had the same pattern, and 11 had heterogeneous patterns. Of the 19 recoverable, nonserotypeable biotype II isolates (6.8% of the total number of H. influenzae), 18 had different OMP patterns, and no pattern was similar to those observed with serotype b. These findings indicate that most H. influenzae strains isolated during this 2-year period were indistinguishable by serotype, biotype, or OMP patterns.  相似文献   
98.
Aspects of the work of five community psychiatric nurses are examined by means of a questionnaire completed by the nurses for a sample of 50 patients. Information sharing and a close working relationship with the general practitioner, skills relating to assessment and psychological support of patients, organization of care by other agencies, a detailed knowledge of community agencies, and a capacity for interdisciplinary working were all found to be important. Tasks relating to body care were reported in only a small number of cases. The nurses saw themselves as advising on the planning of patient management and the selection of medication in a substantial minority of cases. The original brief had been to care for psychogeriatric patients but a third of the patients fell into a younger age group. These findings are discussed in connection with their implications for the future training of nurses and the relationship between primary care teams and local psychiatric services.  相似文献   
99.
100.
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