全文获取类型
收费全文 | 12135篇 |
免费 | 631篇 |
国内免费 | 96篇 |
专业分类
耳鼻咽喉 | 72篇 |
儿科学 | 290篇 |
妇产科学 | 222篇 |
基础医学 | 1401篇 |
口腔科学 | 175篇 |
临床医学 | 771篇 |
内科学 | 3529篇 |
皮肤病学 | 199篇 |
神经病学 | 795篇 |
特种医学 | 385篇 |
外科学 | 2256篇 |
综合类 | 45篇 |
预防医学 | 240篇 |
眼科学 | 76篇 |
药学 | 750篇 |
中国医学 | 28篇 |
肿瘤学 | 1628篇 |
出版年
2024年 | 6篇 |
2023年 | 100篇 |
2022年 | 195篇 |
2021年 | 366篇 |
2020年 | 214篇 |
2019年 | 282篇 |
2018年 | 330篇 |
2017年 | 251篇 |
2016年 | 295篇 |
2015年 | 335篇 |
2014年 | 412篇 |
2013年 | 454篇 |
2012年 | 876篇 |
2011年 | 886篇 |
2010年 | 522篇 |
2009年 | 435篇 |
2008年 | 754篇 |
2007年 | 794篇 |
2006年 | 810篇 |
2005年 | 762篇 |
2004年 | 798篇 |
2003年 | 757篇 |
2002年 | 780篇 |
2001年 | 130篇 |
2000年 | 66篇 |
1999年 | 138篇 |
1998年 | 180篇 |
1997年 | 142篇 |
1996年 | 123篇 |
1995年 | 90篇 |
1994年 | 89篇 |
1993年 | 70篇 |
1992年 | 53篇 |
1991年 | 44篇 |
1990年 | 42篇 |
1989年 | 26篇 |
1988年 | 26篇 |
1987年 | 25篇 |
1986年 | 23篇 |
1985年 | 17篇 |
1984年 | 30篇 |
1983年 | 12篇 |
1982年 | 20篇 |
1981年 | 17篇 |
1980年 | 20篇 |
1979年 | 17篇 |
1978年 | 7篇 |
1977年 | 12篇 |
1976年 | 5篇 |
1974年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
High-frequency inter-parental recombination between mitochondrial genomes of rice cybrids 总被引:2,自引:0,他引:2
Analyzing more than 100 independent rice cybrids, we found evidence for inter-molecular recombination between parental mitochondrial genomes occurring at high frequency soon after protoplast fusion. The structure of the region around the atp6 gene showed extensive polymorphism among Indica (MTC-5A), Japonica (Nipponbare), and wild abortive (IR58024A) mitochondrial genomes. Recombination between the mitochondrial genomes of IR58024A and MTC-5A around the atp6 gene was detected by Southern-blot analysis of cybrid plants. Such recombinant mitochondrial molecules were also cloned from IR58024A/Nipponbare cybrid callus. PCR analysis around the atp6 gene demonstrated that inter-parental recombination occurs in practically all cybrid calli within 2 weeks after protoplast fusion. At this point, parental and recombinant mitochondrial genomes coexisted within the callus. Over the course of further cultivation, however, mitochondrial genome diversity decreased as parental and/or recombinant genomes segregated out. 相似文献
72.
Shunsuke Imai Susumu Sekigawa Hiroaki Yamamoto Yoshihiko Tsubura Michiyo Miyanaga Nobuhiro Narita Riichiro Mikami 《Pathology international》1982,32(4):677-682
An autopsy case of bronchiolo-alveolar adenocarcinoma in the lung is reported. The patient is a 70-year-old male who complained of severe cough with 500–600 ml watery sputum a day, loss of weight, and general fatigue. Autopsy revealed numerous whitish tumors in various sizes with multiple cysts in both lungs, with no metastasis being found in any other organs. Histological findings identified the tumor as a bronchiolo-alveolar adenocarcinoma originating from the lungs. Electron-microscopic findings showed that the tumor cells were covered by prominent microvilli, and contained abundant irregulary-shaped cytoplasmic vacuoles suggestive of mucin. 相似文献
73.
74.
Shibahara H Tsunoda T Taneichi A Hirano Y Ohno A Takamizawa S Yamaguchi C Tsunoda H Sato I 《American journal of reproductive immunology (New York, N.Y. : 1989)》2002,47(3):146-150
PROBLEM: The presence of antisperm antibodies (ASA) in males can reduce fecundity, however, relationship between the two is disputed. This study was performed to investigate if there is diversity of ASA bound to sperm surface using immunobead test (IBT) combined with complement dependent sperm immobilization test (SIT). METHODS: The ASA bound to sperm surface were detected using the direct IBT (D-IBT) in 275 semen samples. In some cases with ASA detected by D-IBT, sperm immobilizing antibodies bound to sperm surface were also evaluated using direct SIT (D-SIT). RESULTS: The incidence of the immunoglobulin G (IgG), IgA, and IgM classes of ASA detected by D-IBT were 2.5, 1.8, and 0.4%, respectively. Totally, nine (3.3%) infertile men had ASA on the sperm surface. D-SIT was tested positive in four (66.7%) of six cases with ASA assessed by D-IBT. CONCLUSIONS: Some of the sperm-bound antibodies are associated with complement dependent sperm immobilizing antibodies, indicating that there exists a heterogeneity of sperm-bound antibodies. This result might be one of the reasons for the controversy about the relationship between ASA and immunological infertility in men. 相似文献
75.
Tokita H Murai S Kamitsukasa H Yagura M Harada H Takahashi M Okamoto H 《Journal of medical virology》2002,67(4):501-509
The TT virus (TTV) load was estimated in sera obtained from 237 patients with hepatitis C virus (HCV)-related chronic liver disease including 42 patients with hepatocellular carcinoma (HCC), by real-time detection PCR using primers and a probe derived from the well-conserved untranslated region of the TTV genome, which can detect all known TTV genotypes. Of the 237 patients studied, 18 (8%) were negative for TTV DNA, 87 (37%) had low TTV viremia (1.3 x 10(2)-9.9 x 10(3) copies/ml), and 132 (56%) had high TTV viremia (1.0 x 10(4)-2.1 x 10(6) copies/ml). Various features were compared between the patients with high TTV load (n = 132) and those with no TTV viremia or low viral load (n = 105). High TTV viremia (> or =10(4) copies/ml) was significantly associated with higher age (P < 0.05), past history of blood transfusion (P < 0.001), complication of cirrhosis (P < 0.05) or HCC (P < 0.0005), lower HCV RNA titer (P < 0.05), and lower platelet count (P < 0.01). On multivariate logistic regression analysis, high TTV viral load was a significant risk factor for HCC (P < 0.05), independent from known risk factors such as complication of liver cirrhosis (P < 0.0001) and high age (> or =65 years, P < 0.05), among all 237 patients. Furthermore, high TTV viral load was an independent risk factor for HCC among the 90 cirrhotic patients (P < 0.05). These results suggest that a high TTV viral load is associated independently with the complication of HCC and may have prognostic significance in patients with HCV-related chronic liver disease, although whether high TTV viremia mediates the progression of HCV-related chronic liver disease remains to be defined. 相似文献
76.
ACh receptor protein drives primary and memory autoantibody responses in chimeric human-SCID mice 总被引:1,自引:0,他引:1
The native antigen that drives the T-helper cells regulating production of muscle acetylcholine receptor (AChR) autoantibodies is unknown. Human T cell lines activated by autoantigens in vitro are of unproven relevance to B cell help. Here we report the functional interaction and unprecedented longevity of AChR-specific human T and B lymphocytes residing in SCID mice. Lymphoid cells from myasthenia gravis (MG) patients and healthy subjects were injected ip. Recombinant human AChR-alpha1-subunit-1-210 was injected after day 75. Human AChR-specific Ig was produced rapidly in MG-SCID mice challenged once. Only 1 of 32 control hu-SCID mice produced AChR-specific Ig. This required multiple immunizations, was initially cross-reactive with Torpedo AChR, and had a slow course. Thus, memory T and B lymphocytes specific for human AChR-alpha1-subunit are readily demonstrable in MG patients, interact to produce autoantibody of the same restricted specificity found in the donor's serum, and are long-lived without exogenous autoantigen challenge. In healthy subjects, AChR-specific lymphocytes are infrequent and exhibit naive response characteristics, including apparent affinity maturation of Ig specificity. 相似文献
77.
To help understand the molecular mechanisms of Pasteurella multocida toxin (PMT) action, we searched for a cellular protein interacting with PMT. The ligand overlay assay revealed a 60-kDa cellular protein that binds to a region from the 840th to 985th amino acids of the toxin. This protein was identified as vimentin by peptide mass fingerprinting. The N-terminal head domain of vimentin was further found to be responsible for the binding to the toxin. 相似文献
78.
Atsuko Iwasa Yoshinao Oda Shuichi Kurihara Yoshihiro Ohishi Masafumi Yasunaga Izumi Nishimura Emi Takagi Hiroaki Kobayashi Norio Wake Masazumi Tsuneyoshi 《Pathology international》2008,58(12):757-764
Ovarian mature cystic teratomas (MCT) uncommonly undergo malignant transformation to squamous cell carcinoma (SCC). While alterations in the p53 tumor suppressor gene and protein have been shown, few studies have analyzed other molecular changes leading to this malignant conversion. The purpose of the present study was to investigate 21 samples of SCC arising in MCT for altered expression in known p53‐ and p16/Rb‐dependent cell cycle regulatory proteins, and the association between their expression and cellular proliferation and histological features. Overexpression of the p53 protein was observed in 14 SCC (67%), while four (19%) had point mutations in the p53 gene. Reduced expression of the p16 protein was observed in 18 SCC (86%), while p16 gene alterations (hypermethylation (29%) and point mutation (33%)) were found in 11 (52%). Furthermore, a statistically significant correlation was observed between p53 and Rb overexpression (P = 0.0010), and the overexpression of both p53 and Rb was respectively significantly correlated with increased cellular proliferation. The results indicate that alterations in both the p53 and p16‐Rb pathways are associated with SCC arising in MCT. 相似文献
79.
Susumu Harada Maya Iijima Akiko Nakamura Yoshitsugu Yoshizaki Hiroaki Matsuo Eisin Morita 《Arerugī》2007,56(1):41-48
BACKGROUND: Either omega-5 gliadin or high molecular weight glutenin is known to be a major allergen in wheat-dependent exercise-induced anaphylaxis (WDEIA). It is generally considered that gluten specific IgE score is more reliable than that of wheat specific IgE score for the diagnosis of WDEIA. Our aim was to verify the significance of gluten specific IgE in the diagnosis of WDEIA. METHODS: We evaluated the result of gluten CAP-RAST score and omega-5 gliadin specific IgE score on four WDEIA patients who visited our hospital during the years 2004 and 2005, whose diagnosis were onfirmed by prick tests, immunoblot tests and provocation tests. RESULTS: Contrary to our expectations, all four patients showed negative gluten CAP-RAST scores, however all patient's omega-5 gliadin specific IgE scores were positive. CONCLUSION: Our results suggest that gluten specific CAP-RAST score is unreliable in the diagnosis of WDEIA. On the other hand omega-5 gliadin specific IgE score is possibly a better candidate as a diagnostic tool for WDEIA. 相似文献
80.