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   3133篇
  免费   211篇
  国内免费   3篇
  2023年   61篇
  2022年   30篇
  2021年   62篇
  2020年   57篇
  2019年   54篇
  2018年   126篇
  2017年   117篇
  2016年   159篇
  2015年   117篇
  2014年   149篇
  2013年   324篇
  2012年   221篇
  2011年   257篇
  2010年   223篇
  2009年   133篇
  2008年   147篇
  2007年   131篇
  2006年   125篇
  2005年   96篇
  2004年   104篇
  2003年   105篇
  2002年   93篇
  2001年   45篇
  2000年   49篇
  1999年   25篇
  1998年   18篇
  1997年   11篇
  1996年   16篇
  1995年   15篇
  1994年   16篇
  1993年   23篇
  1992年   20篇
  1991年   13篇
  1990年   8篇
  1988年   12篇
  1986年   5篇
  1985年   13篇
  1984年   11篇
  1983年   10篇
  1982年   11篇
  1981年   7篇
  1980年   5篇
  1978年   9篇
  1977年   10篇
  1976年   5篇
  1975年   12篇
  1974年   8篇
  1973年   6篇
  1972年   12篇
  1971年   11篇
排序方式: 共有3347条查询结果,搜索用时 427 毫秒
61.
Molecular Biology Reports - Heat shock protein 90 (Hsp90) is a key chaperone that is abnormally expressed in cancer cells, and therefore, designing novel compounds to inhibit chaperone activities...  相似文献   
62.

Ischemic infarctions occur under the influence of genetic and environmental factors. In our study, the role of ischemia-modified albumin and thiol balance, which are new markers in determining oxidative damage together with MTHFR gene polymorphisms and homocysteine levels, in the development of SBI was investigated. White matter lesions in the magnetic resonance imaging (MRI) results of the patients were evaluated according to the Fazekas scale and divided into groups (Grade 0, 1, 2, and 3). Homocysteine, folate, B12, IMA, total thiol, and native thiol were measured by biochemical methods. The polymorphisms in MTHFR genes were investigated by the RT-PCR method. According to our results, a significant difference was found between the groups in age, homocysteine, folate, IMA, total thiol, and native thiol parameters (p?<?0.05). When we compared the groups in terms of genotypes of the C677T gene, we found a significant difference in TT genotype between grades 0/3 and 1/3 (p?<?0.05). We determined that homocysteine and IMA levels increased and folate levels decreased in CC/TT and CT/TT genotypes in the C677T gene (p?<?0.05). Considering our results, the observation of homocysteine and IMA changes at the genotype level of the MTHFR C677T gene and between the groups, and the deterioration of thiol balance between the groups suggested that these markers can be used in the diagnosis of silent brain infarction.

  相似文献   
63.

The introduction of invasive exotic species can have strong ecological impacts on the native biota, with direct consequences for commercial fisheries. Feeding ecology studies are among the primary sources for improving predictions related to community structures, for example, by revealing potential competitive interactions between native and invasive species. We compared the stomach contents and studied diet overlaps among a native (Mullus barbatus) and two invasive (Upeneus moluccensis and U. pori) mullid species, collected off the coasts of the northeastern Levantine where invasive mullids have been part of the ecosystem for more than half a century. We also assessed the effect of sex, sampling period, depth and size on stomach contents. Schoener’s index indicated significant diet overlaps between U. moluccensisU. pori and U. moluccensisM. barbatus. Diets of U. pori and M. barbatus did not significantly overlap, which was explained by their differing depth preferences. Assessment of stomach contents showed that Crustacea, specifically Decapoda, was the main prey group across the studied mullid species. Polychaeta was also of high importance in the diet of the native M. barbatus, but not for the two invasive Upeneus species. A trophic level analysis revealed the two invasive mullids to have a higher trophic level than the native species (U. moluccensis: 3.58, U. pori: 3.55 versus M. barbatus: 3.38). The lack of a clear separation in habitat and diet preferences documented here between native and invasive mullids may pose a risk for the persistence of the economically valuable native M. barbatus in the Mediterranean Sea.

  相似文献   
64.
65.

Osteoarthritis (OA) is a common condition that impacts many people worldwide and involves weight-bearing joints, resulting in chronic pain. In this study, we aimed to compare the effectiveness of inpatient and outpatient physical therapy modalities and spa combination treatments on pain and functional status in patients with knee osteoarthritis. Seventy-four patients diagnosed with primary knee osteoarthritis were included in this study. The patients were randomized into two groups, inpatient (n?=?37) and outpatient (n?=?37) physical therapy. All patients received a physical therapy program (superficial heater + deep heater + transcutaneous electrical nerve stimulation) for 2 weeks and spa therapy. All cases were evaluated clinically, laboratory, and radiographically. In order to evaluate pain and functional status, the Visual Analogue Scale (VAS), Western Ontario and McMaster Universities osteoarthritis index (WOMAC), and Timed Up and Go (TUG) test were used before and after treatment. There was no significant difference between the two groups in the TUG test and WOMAC scores (p?>?0.05). However, a significant difference was found in VAS scores in favor of the outpatient group (p?<?0.05). As a result, although there was a significant improvement in pain scores in the outpatient group, multicenter studies with larger patient groups may provide more evidence.

  相似文献   
66.
International Journal of Biometeorology - Epidemiological studies have suggested an association between particulate air pollution, increased temperatures, and morbidity related to pregnancy...  相似文献   
67.
Nanocarriers for encapsulation and sustained release of agrochemicals such as auxins have emerged as an attractive strategy to provide enhanced bioavailability and efficacy for improved crop yields and nutrition quality. Here, a comparative study was conducted on the effectiveness of chitosan-as a biopolymeric nanocarrier- and silver-as a metallic nanocarrier- on in vitro adventitious rooting potential of microcuttings in apple rootstocks, for the first time. Auxins indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA) loaded silver (nAg) or chitosan nanoparticles (nChi) were synthesized. Scanning electron microscopy and transmission electron microscopy studies showed the spherical shape of the nanoparticles. The average particle size of IAA-nChi was 167.5 ± 0.1 nm while that of IBA-nChi was 123.2 ± 2.6 nm. The hydrodynamic diameter of the nAg-IAA and nAg-IBA particles were measured as 93.66 ± 5 nm and 71.41 ± 3 nm, respectively. Fourier transform infrared spectroscopy analyses confirmed the encapsulation of IAA or IBA in the chitosan nanoparticles. Meanwhile, the characteristic peaks of IAA or IBA were detected on silver nanoparticles. In-vitro adventitious rooting of microcuttings of Malling Merton 106 (MM 106) was significantly higher both in chitosan and silver nanoparticles loaded with IAA or IBA (91.7%–62.5%) compared to free IAA or IBA applications (50.0%–33.3%), except for 2.0 mg L–1 IBA (66.7%). However, the application of 2 mg L–1 IBA and IBA-nChi at all concentrations caused an undesirable large callus development.  相似文献   
68.
Therapies that utilize immune checkpoint inhibition work by leveraging mutation-derived neoantigens and have shown greater clinical efficacy in tumors with higher mutational burden. Whether tumors with a low mutational burden are susceptible to neoantigen-targeted therapy has not been fully addressed. To examine the feasibility of neoantigen-specific adoptive T-cell therapy, the authors studied the T-cell response against somatic variants in five patients with myelodysplastic syndrome (MDS), a malignancy with a very low tumor mutational burden. DNA and RNA from tumor (CD34+) and normal (CD3+) cells isolated from the patients’ blood were sequenced to predict patient-specific MDS neopeptides. Neopeptides representing the somatic variants were used to induce and expand autologous T cells ex vivo, and these were systematically tested in killing assays to determine the proportion of neopeptides yielding neoantigen-specific T cells. The authors identified a total of 32 somatic variants (four to eight per patient) and found that 21 (66%) induced a peptide-specific T-cell response and 19 (59%) induced a T-cell response capable of killing autologous tumor cells. Of the 32 somatic variants, 11 (34%) induced a CD4+ response and 11 (34%) induced a CD8+ response that killed the tumor. These results indicate that in vitro induction of neoantigen-specific T cells is feasible for tumors with very low mutational burden and that this approach warrants investigation as a therapeutic option for such patients.  相似文献   
69.
International Journal of Peptide Research and Therapeutics - The clinical application of some natural molecules in therapy is usually limited due to the lack of feasible delivery systems....  相似文献   
70.
The antioxidant and mutagenic/antimutagenic activities of the fixed oils from Nigella sativa (NSO) and Nigella damascena (NDO) seeds, obtained by cold press-extraction from the cultivar samples, were comparatively investigated for the first time. The antimutagenicity test was carried out using classical and modified Ames tests. The fatty acid composition of the fixed oils was characterized by gas chromatography–mass spectrometry (GC-MS) while the quantification of thymoquinone in the fixed oils was determined by UPC2. The main components of the NSO and NDO were found to be linoleic acid, oleic acid, and palmitic acid. The results of the Ames test confirmed the safety of NSO and NDO from the viewpoint of mutagenicity. The results of the three antioxidant test methods were correlated with each other, indicating NDO as having a superior antioxidant activity, when compared to the NSO. Both NSO and NDO exhibited a significant protective effect against the mutagenicity induced by aflatoxin B1 in Salmonella typhimurium TA98 and TA100 strains. When microsomal metabolism was terminated after metabolic activation of the mycotoxin, a significant increase in antimutagenic activity was observed, suggesting that the degradation of aflatoxin B1 epoxides by these oils may be a possible antimutagenic mechanism. It is worthy to note that this is the first study to assess the mutagenicity of NSO and NDO according to the OECD 471 guideline and to investigate antimutagenicity of NDO in comparison to NSO against aflatoxin.  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