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   6461篇
  免费   302篇
  国内免费   55篇
耳鼻咽喉   35篇
儿科学   145篇
妇产科学   155篇
基础医学   882篇
口腔科学   126篇
临床医学   529篇
内科学   1616篇
皮肤病学   108篇
神经病学   486篇
特种医学   373篇
外科学   902篇
综合类   29篇
预防医学   250篇
眼科学   71篇
药学   488篇
中国医学   19篇
肿瘤学   604篇
  2023年   34篇
  2022年   71篇
  2021年   120篇
  2020年   70篇
  2019年   85篇
  2018年   92篇
  2017年   80篇
  2016年   117篇
  2015年   112篇
  2014年   169篇
  2013年   181篇
  2012年   290篇
  2011年   385篇
  2010年   201篇
  2009年   181篇
  2008年   300篇
  2007年   334篇
  2006年   318篇
  2005年   338篇
  2004年   368篇
  2003年   347篇
  2002年   298篇
  2001年   189篇
  2000年   195篇
  1999年   171篇
  1998年   72篇
  1997年   80篇
  1996年   60篇
  1995年   41篇
  1994年   42篇
  1993年   39篇
  1992年   104篇
  1991年   121篇
  1990年   123篇
  1989年   89篇
  1988年   95篇
  1987年   89篇
  1986年   97篇
  1985年   85篇
  1984年   65篇
  1983年   48篇
  1982年   28篇
  1979年   36篇
  1978年   36篇
  1977年   37篇
  1975年   33篇
  1974年   40篇
  1972年   42篇
  1971年   36篇
  1968年   34篇
排序方式: 共有6818条查询结果,搜索用时 15 毫秒
121.
Cholesteryl ester transfer protein (CETP) is one of the factors that regulate plasma levels of HDL-cholesterol. To identify the factors that may regulate CETP activity, and to determine to what extent CETP is correlated with physiologic concentrations of lipoprotein, we performed an epidemiologic study in 586 healthy volunteers (317 males and 269 females, mean age 52.2 ± 10.9 years). CETP activity in these subjects was 192.96 ± 48.73 (mean ± S.D.) nmol/ml/h and distributed to a wide range (60–450 nmol/ml/h). Using multiple regression analysis, we found significant positive correlations between CETP activity and LDL-cholesterol (P < 0.03), apolipoprotein (apo) E (P < 0.005) and LCAT activity (P < 0.001). CETP activities showed significant negative correlation with apo A-I (P < 0.03). However, CETP activity showed no significant correlation either with HDL cholesterol or with apo B. One-way layout analysis of variance showed that alcohol drinking and cigarette smoking significantly reduced CETP activity, but there was no significant association between CETP activity and body mass index. Although CETP activities were significantly higher in females than in males (P < 0.001), multiple regression analysis showed no correlation between CETP activity and age in either the males or the females. Our results suggest that CETP activity regulates the concentration of apo A-I and LDL-cholesterol, and that such activity may be influenced by gender, alcohol consumption and cigarette smoking.  相似文献   
122.
Many patients with smear positive tuberculosis were hospitalized during the initial phase of chemotherapy but DOT was not applied to patients with tuberculosis in Japan. We tried randomized clinical study to evaluate the usefulness of DOT during admission. 135 culture positive TB patients were administered by DOT and 124 culture positive TB patients were self-administered during admission. There was no significant difference between 2 groups in the clinical background factors, treatment and the incidence of adverse reactions. Treatment completion rate was 94.1% in DOT group and 87.9% in non-DOT group. Default rate was significantly lower in DOT group (4.4%) than in non-DOT group (11.3%). We concluded that "DOT during admission" was useful to improve the outcome of chemotherapy for tuberculosis and it is preferable to apply DOT throughout treatment course for patients with tuberculosis in Japan.  相似文献   
123.

Aim

This study aimed to examine female high school students’ behavioral intention to prevent cervical cancer and related factors.

Methods

The participants were 2158 female high school students at 16 high schools in A prefecture in the Tohoku region in Japan. A self‐administered questionnaire was carried out that was developed based on a conceptual framework comprising the Health Belief Model and Theory of Reasoned Action.

Results

The responses were obtained from 2072 students (96.0%). Of these, the answers of 2028 respondents were analyzed after excluding those participants who did not complete the behavioral intention item (effective response rate: 97.0%). A factor analysis and covariance structure analysis yielded a model with strong goodness‐of‐fit that explained the behavioral intentions based on an “Awareness of the importance and effectiveness of cervical cancer screening,” “Obstacles to cervical cancer prevention behavior,” “Subjective norms for adopting cervical cancer prevention behavior,” and “The behavior of someone close that encourages cervical cancer prevention behavior.”

Conclusion

The statistical analysis yielded a model with strong goodness‐of‐fit that explained female high school students’ behavioral intentions, which were related to four factors, including “the awareness of the importance and effectiveness of cervical cancer screening.”
  相似文献   
124.
Exposure to ionizing radiation during childhood is a well-known risk factor for thyroid cancer. Our study evaluated the effect of age on the radiosensitivity of rat thyroid glands. Four-week-old (4W), 7 -week-old (7W), and 8-month-old (8M) male Wistar rats were exposed to 8 Gy of whole-body X-ray irradiation. Thyroids were removed 3–72 h after irradiation, and non-irradiated thyroids served as controls. Ki67-positivity and p53 binding protein 1 (53BP1) focus formation (a DNA damage response) were evaluated via immunohistochemistry. Amounts of proteins involved in DNA damage response (p53, p53 phosphorylated at serine 15, p21), apoptosis (cleaved caspase-3), and autophagy (LC3, p62) were determined via western blotting. mRNA levels of 84 key autophagy-related genes were quantified using polymerase chain reaction arrays. Ki67-positive cells in 4W (with high proliferative activity) and 7W thyroids significantly decreased in number post-irradiation. The number of 53BP1 foci and amount of p53 phosphorylated at serine 15 increased 3 h after irradiation, regardless of age. No increase in apoptosis or in the levels of p53, p21 or cleaved caspase-3 was detected for any ages. Levels of LC3-II and p62 increased in irradiated 4W but not 8M thyroids, whereas expression of several autophagy-related genes was higher in 4W than 8M irradiated thyroids. Irradiation increased the expression of genes encoding pro-apoptotic proteins in both 4W and 8M thyroids. In summary, no apoptosis or p53 accumulation was noted, despite the expression of some pro-apoptotic genes in immature and adult thyroids. Irradiation induced autophagy in immature, but not in adult, rat thyroids.  相似文献   
125.

Background and Purpose

Elevation of glutamate, an excitatory amino acid, during inflammation and injury plays a crucial role in the reception and transmission of sensory information via ionotropic and metabotropic receptors. This study aimed to investigate the mechanisms underlying the biphasic effects of metabotropic glutamate mGlu5 receptor activation on responses to noxious heat.

Experimental Approach

We assessed the effects of intraplantar quisqualate, a non-selective glutamate receptor agonist, on heat and mechanical pain behaviours in mice. In addition, the effects of quisqualate on the intracellular calcium response and on membrane currents mediated by TRPV1 channels, were examined in cultured dorsal root ganglion neurons from mice.

Key Results

Activation of mGlu5 receptors in hind paw transiently increased, then decreased, the response to noxious heat. In sensory neurons, activation of mGlu5 receptors potentiated TRPV1-mediated intracellular calcium elevation, while terminating activation of mGlu5 receptors depressed it. TRPV1-induced currents were potentiated by activation of mGlu5 receptors under voltage clamp conditions and these disappeared after washout. However, voltage-gated calcium currents were inhibited by the mGlu5 receptor agonist, even after washout.

Conclusions and Implications

These results suggest that, in sensory neurons, mGlu5 receptors biphasically modulate TRPV1-mediated intracellular calcium response via transient potentiation of TRPV1 channel-induced currents and persistent inhibition of voltage-gated calcium currents, contributing to heat hyper- and hypoalgesia.  相似文献   
126.
127.
128.
Journal of Gastroenterology - REFLECT was an open-label, phase 3 study comparing the efficacy and safety of lenvatinib versus sorafenib in patients with unresectable hepatocellular carcinoma...  相似文献   
129.
Solitary organ autoimmune disorders, formerly known as autoimmune pancreatitis (AIP), autoimmune sialadenitis, and autoimmune sclerosing cholangitis, are now considered organ-specific manifestations of systemic immunoglobulin G4-related disease (IgG4-RD). AIP and IgG4-RD are characterized by elevated serum concentration of IgG4 antibody (Ab), accumulation of IgG4-expressing plasmacytes in the affected organs, and involvement of multiple organs. It is well established that enhanced IgG4 Ab responses are a hallmark of AIP and IgG4-RD for diagnosis and monitoring disease activity. However, a significant fraction of patients with AIP and IgG4-RD who develop chronic fibroinflammatory responses have normal serum concentrations of this IgG subtype. In addition, disease flare-up is sometimes seen even in the presence of normalized serum concentrations of IgG4 Ab after successful induction of remission by prednisolone. Therefore, it is necessary to identify new biomarkers based on the understanding of the pathophysiology of AIP and IgG4-RD. Recently, we found that activation of plasmacytoid dendritic cells producing both interferon-α (IFN-α) and interleukin-33 (IL-33) mediate murine AIP and human IgG4-RD. More importantly, we provided evidence that serum concentrations of IFN-α and IL-33 could be useful biomarkers for the diagnosis and monitoring of AIP and IgG4-RD activity after induction of remission in these autoimmune disorders. In this Frontier article, we have summarized and discussed biomarkers of AIP and IgG4-RD, including Igs, autoAbs, and cytokines to provide useful information not only for clinicians but also for researchers.  相似文献   
130.
The educational system and the introduction of legislation of clinical medicine are both still in developing stage in Cambodia where only 10 years have passed since the establishment of a new government. In order to maintain good health of all Cambodian citizens and to improve the quality of care in health services, it should be necessary to implement an appropriate educational system for both laboratory technologists and technicians. To conduct refreshment training course for laboratory workers with provision of the instruments, material and reagents is another way to make improvement of it in public hospitals. It should be also required to overcome economic problems how to absorb medical expense and to understand the importance for doctors to diagnose with scientific data of clinical examinations. Maturation of the total medical system in this country should be necessary and suggestions from neighboring countries with views toward the world standard would be expected.  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