全文获取类型
收费全文 | 14853篇 |
免费 | 811篇 |
国内免费 | 101篇 |
专业分类
耳鼻咽喉 | 157篇 |
儿科学 | 344篇 |
妇产科学 | 217篇 |
基础医学 | 1803篇 |
口腔科学 | 226篇 |
临床医学 | 948篇 |
内科学 | 4268篇 |
皮肤病学 | 363篇 |
神经病学 | 975篇 |
特种医学 | 473篇 |
外科学 | 2631篇 |
综合类 | 57篇 |
预防医学 | 329篇 |
眼科学 | 127篇 |
药学 | 946篇 |
中国医学 | 36篇 |
肿瘤学 | 1865篇 |
出版年
2023年 | 111篇 |
2022年 | 219篇 |
2021年 | 406篇 |
2020年 | 235篇 |
2019年 | 316篇 |
2018年 | 397篇 |
2017年 | 292篇 |
2016年 | 334篇 |
2015年 | 381篇 |
2014年 | 475篇 |
2013年 | 511篇 |
2012年 | 963篇 |
2011年 | 996篇 |
2010年 | 588篇 |
2009年 | 507篇 |
2008年 | 868篇 |
2007年 | 917篇 |
2006年 | 928篇 |
2005年 | 887篇 |
2004年 | 926篇 |
2003年 | 875篇 |
2002年 | 895篇 |
2001年 | 238篇 |
2000年 | 167篇 |
1999年 | 240篇 |
1998年 | 212篇 |
1997年 | 163篇 |
1996年 | 144篇 |
1995年 | 117篇 |
1994年 | 109篇 |
1993年 | 82篇 |
1992年 | 112篇 |
1991年 | 106篇 |
1990年 | 87篇 |
1989年 | 74篇 |
1988年 | 67篇 |
1987年 | 72篇 |
1986年 | 60篇 |
1985年 | 69篇 |
1984年 | 63篇 |
1983年 | 34篇 |
1982年 | 40篇 |
1981年 | 36篇 |
1980年 | 37篇 |
1979年 | 52篇 |
1977年 | 30篇 |
1972年 | 31篇 |
1970年 | 40篇 |
1969年 | 30篇 |
1968年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Takaaki Ohmori Kazuyo Okada Ryo Tabei Keisuke Sugiura Shinji Nabeshima Hiroji Ohoka Masaki Okamoto 《Pathology international》1994,44(4):333-337
A case of primary seminal vesicle carcinoma is reported. The tumor was a CA125-producing adenocarcinoma consisting of fine papillary-tubular, intricate branching or anastomosing glandular structures and was composed of small cuboidal, but occasionally hobnailed, cells with mostly clear, but occasionally granular, cytoplasm. Some tumor cells showed evidence of secretion of seromucinous materials into the interpapillary and cystic space. lmmunohistochemically, almost half of the tumor cells expressed a positive reaction with anti-CAl25, a common serological marker for ovarian epithelial carcinomas; however, no tumor cells expressed any other serological tumor markers such as carcinoem-bryonic antigen, α-fetoprotein, human chorionic gonadotropin, prostatic specific acid phosphatase, or prostatic specific antigen. The patient showed a high level of serological CA125, which fluctuated parallel with the growth, removal and recurrence of the tumor. The morphological and immunohistochemical findings suggested a close relationship between the present tumor and clear cell carcinoma of the ovary, which is thought to be of a Müllerian-Wolfian duct origin. 相似文献
102.
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
103.
Identification of the defects in the hemagglutinin gene of two temperature-sensitive mutants of A/WSN/33 influenza virus 总被引:4,自引:0,他引:4
S Nakajima D J Brown M Ueda K Nakajima A Sugiura A K Pattnaik D P Nayak 《Virology》1986,154(2):279-285
Two temperature-sensitive mutants of WSN influenza virus, ts-61S and ts-134, possess defects in the hemagglutinin (HA) gene. These defects are characterized as a defective intracellular transport of the HA at the nonpermissive temperature and a marked thermolability. The nucleic acid sequences of the HA gene of these two viruses, as well as a series of revertant viruses, were determined. The deduced amino acid sequences demonstrate that the HA of ts-61S varied from the wild type protein by three amino acids while that of ts-134 differed by two residues. For both mutants, analysis of revertant viruses indicated that the phenotype of transport inhibition at the nonpermissive temperature and heat lability were associated with a single amino acid change in the globular portion of the molecule. In the case of ts-61S, the critical change in the HA was the replacement of a serine residue at position 110 with that of a proline. The mutational defect in the HA of ts-134 was due to the substitution of a tyrosine residue at position 159 with that of a histidine residue. Four of five revertants of ts-134 were suppressor revertants, of which some of the compensatory changes did not restore thermostability to the HA. 相似文献
104.
105.
Summary We have compared the kinetic growth patterns of To-336, MEQ11, KRT, and SK2 rubella vaccine strains licensed in Japan at 37° and 39° C with those of progenitor wild strains of rubella virus. The growth of vaccine strains was depressed at 39° C to a level about 3 log10 lower than that at 37° C. The difference in virus titer attained by wild strains at 37° and 39° C was less than tenfold. The growth potential at 39° C paralleled the immunogenic marker of rubella virus,i.e. the capability of virus to induce antibody response upon subcutaneous injection in rabbits for all wild and vaccine strains examined, including one strain at an intermediate level of attenuation. Several clones were isolated from the progeny produced by a vaccine strain during the growth at 39° C. Among them were partial revertants in immunogenic marker as well as in the growth potential at 39° C. It was concluded that the immunogenic marker of rubella virus in rabbits represented its capability to replicate at the body temperature of the animal.With 6 Figures 相似文献
106.
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
107.
Yoshida M Sagawa N Itoh H Yura S Takemura M Wada Y Sato T Ito A Fujii S 《Molecular human reproduction》2002,8(7):681-687
Human uterine cervical tissue is composed mainly of fibroblast cells and the extracellular matrix in which collagen types I and III predominate. It is hypothesized that these collagens are degraded by matrix metalloproteinases (MMPs) in the initial step of uterine cervical ripening during parturition. Among the MMPs, MMP-1, -8 and -13 have substrate selectivity for collagen types I and III. In the present study, we examined the regulation of MMP-1 secretion from the human uterine cervix. Immunohistochemistry detected strong staining of MMP-1, but not of MMP-8 or -13, in stromal cells of the pregnant uterine cervix. The MMP-1 expression in the pregnant uterine cervix was further confirmed by Western blot analysis and RT-PCR. To clarify the regulation of MMP-1 production, we subsequently investigated the effects of prostaglandins, inflammatory cytokines and cyclic mechanical stretch on the secretion of MMP-1 from cultured human uterine cervical fibroblast cells. Treatment with prostaglandin (PG)F(2alpha) (10(-7) to 10(-5) mol/l) or interleukin (IL)-1alpha (0.01-1.0 ng/ml) or stimulation with cyclic mechanical stretch increased MMP-1 secretion from cultured human uterine cervical fibroblast cells, with maximal increases of 3.4-, 4.5- and 1.9-fold respectively (24 h of treatment, P < 0.05 for all comparisons). These data suggest that MMP-1 may play a significant role in the degradation of extracellular collagen types I and III in the pregnant uterine cervix during the process of cervical ripening, in response to various stimulations such as PGF(2alpha), IL-1alpha and mechanical stretch. 相似文献
108.
109.
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
110.
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