全文获取类型
收费全文 | 8096篇 |
免费 | 384篇 |
国内免费 | 65篇 |
专业分类
耳鼻咽喉 | 105篇 |
儿科学 | 152篇 |
妇产科学 | 69篇 |
基础医学 | 1304篇 |
口腔科学 | 191篇 |
临床医学 | 501篇 |
内科学 | 2219篇 |
皮肤病学 | 141篇 |
神经病学 | 573篇 |
特种医学 | 341篇 |
外科学 | 1301篇 |
综合类 | 17篇 |
预防医学 | 191篇 |
眼科学 | 100篇 |
药学 | 443篇 |
中国医学 | 27篇 |
肿瘤学 | 870篇 |
出版年
2023年 | 55篇 |
2022年 | 93篇 |
2021年 | 142篇 |
2020年 | 75篇 |
2019年 | 112篇 |
2018年 | 140篇 |
2017年 | 128篇 |
2016年 | 141篇 |
2015年 | 182篇 |
2014年 | 233篇 |
2013年 | 321篇 |
2012年 | 410篇 |
2011年 | 422篇 |
2010年 | 251篇 |
2009年 | 238篇 |
2008年 | 399篇 |
2007年 | 497篇 |
2006年 | 498篇 |
2005年 | 457篇 |
2004年 | 490篇 |
2003年 | 460篇 |
2002年 | 496篇 |
2001年 | 174篇 |
2000年 | 151篇 |
1999年 | 177篇 |
1998年 | 128篇 |
1997年 | 112篇 |
1996年 | 101篇 |
1995年 | 90篇 |
1994年 | 100篇 |
1993年 | 80篇 |
1992年 | 117篇 |
1991年 | 106篇 |
1990年 | 81篇 |
1989年 | 79篇 |
1988年 | 51篇 |
1987年 | 83篇 |
1986年 | 78篇 |
1985年 | 50篇 |
1984年 | 45篇 |
1983年 | 40篇 |
1982年 | 46篇 |
1981年 | 53篇 |
1980年 | 41篇 |
1979年 | 36篇 |
1978年 | 35篇 |
1977年 | 30篇 |
1976年 | 29篇 |
1975年 | 29篇 |
1973年 | 28篇 |
排序方式: 共有8545条查询结果,搜索用时 0 毫秒
71.
Yasuo Kawakami Kimitaka Nakazawa Toshiro Fujimoto Daichi Nozaki Mitsumasa Miyashita Tetsuo Fukunaga 《European journal of applied physiology》1994,68(2):139-147
Series cross-section images of the upper extremity were obtained for four men by magnetic resonance imaging (MRI) and anatomical cross-sectional areas (ACSA) of elbow flexor muscles [biceps brachii (BIC), brachialis (BRA), brachioradialis (BRD)] and extensor muscles [triceps brachii (TRI)] were measured. Physiological cross-sectional area (PCSA) was calculated from the muscle volume and muscle fibre length, the former from the series ACSA and the latter from the muscle length multiplied by previously reported fibre/muscle length ratios. Elbow flexion/extension torque was measured using an isokinetic dynamometer and the force at the tendons was calculated from the torque and moment arms of muscles measured by MRI. Maximal ACSA of TRI was comparable to that of total flexors, while PCSA of TRI was greater by 1.9 times. Within flexors, BRA had the greatest contribution to torque (47%), followed by BIC (34%) and BRD (19%). Specific tension related to the estimated velocity of muscle fibres were similar for elbow flexors and extensors, suggesting that the capacity of tension development is analogous between two muscle groups. 相似文献
72.
Xuan X Larsen A Ikadai H Tanaka T Igarashi I Nagasawa H Fujisaki K Toyoda Y Suzuki N Mikami T 《Journal of clinical microbiology》2001,39(2):705-709
The gene encoding the entire Babesia equi merozoite antigen 1 (EMA-1) was inserted into a baculovirus transfer vector, and a recombinant virus expressing EMA-1 was isolated. The expressed EMA-1 was transported to the surface of infected insect cells, as judged by an indirect fluorescent-antibody test (IFAT). The expressed EMA-1 was also secreted into the supernatant of a cell culture infected with recombinant baculovirus. Both intracellular and extracellular EMA-1 reacted with a specific antibody in Western blots. The expressed EMA-1 had an apparent molecular mass of 34 kDa that was identical to that of native EMA-1. The secreted EMA-1 was used as an antigen in an enzyme-linked immunosorbent assay (ELISA). The ELISA differentiated B. equi-infected horse sera from Babesia caballi-infected horse sera or normal horse sera. The ELISA was more sensitive than the complement fixation test and IFAT. These results demonstrated that the recombinant EMA-1 expressed in insect cells might be a useful diagnostic reagent for detection of antibodies to B. equi. 相似文献
73.
A floating cell line (HGC-25) was established from the metastatic ascitic fluid of a human pancreatic adenocarcinoma of ductal cell origin. The cell line was characterized by the growth in suspension with a doubling time of 15.6 hr, a high cloning efficiency in soft agar and a modal chromosome number of 72. Electron microscopic examination revealed terminal bars in a small number of cells. Production of mucin and immunoglobulins and phagocytosis were not demonstrated. Heterotransplantation of the cells produced tumors, being undifferentiated carcinoma histologically. These characteristics mentioned above confirm that HGC-25 cell line is a human pancreatic cancer ceU line. 相似文献
74.
Naoya Nakamura Naoyoshi Mori Koichi Ohshima Tetsuo Kuze Yuko Hashimoto Yoshikazu Sasaki Asumi Shirakawa Michiko Sato Masafumi Abe 《Diagnostic molecular pathology》2002,11(2):83-89
We examined nucleotide sequences of Epstein-Barr virus (EBV)-positive Hodgkin/Reed-Sternberg (HRS)-like B cells in a case of diffuse large B-cell lymphoma (DLBCL) and a case of adult T-cell lymphoma (ATL) for single-cell polymerase chain reaction of the immunoglobulin heavy-chain gene variable region (VH gene). HRS-like B cells were scattered in the area irrelevant to the lymphoma infiltrates of DLBCL and in the lymphoma area of ATL. HRS-like B cells were positive for CD20 and CD30 but negative for CD15. EBV presented in HRS-like B cells in both cases but not in any lymphoma cells. VH genes of five HRS-like B cells analyzed in DLBCL were polyclonal and showed in-frame sequences with 0% to 2.8% somatic mutation frequency. In an ATL, VH genes of five HRS-like B cells analyzed were polyclonal and somatically mutated. Four cells carried in-frame rearrangements with 3.5% to 17.7% mutation frequency. One of the VH genes has a one-codon deletion. From the fifth cell, an out-of-frame rearrangement with an insertion and a deletion was obtained. Thus, we showed polyclonal EBV-positive HRS-like B cells in both DLBCL and ATL and that whereas EBV-positive, HRS-like B cells in DLBCL exhibited unmutated and mutated VH gene, those in ATL were found to have a somatically mutated VH gene with/without deletions and/or insertions. The HRS-like B cells may appear because of active EBV infection in a patient who is immunosuppressed from the primary lymphoma. 相似文献
75.
Monoclonal antibodies(moAbs) reactive with melatonin(MT) were produced using MT, coupled to bovine serum albumin(BSA) with the Mannich reaction, as immunogen and conventional hybridoma techniques. Hybridoma clones secreting the moAbs were selected by an enzyme-linked immunosorbent assay system using MT-carboxymethylchitin and BSA as screening antigens. The moAbs from 6 clones were characterized by a cross-reactivity test using radioimmunoassay with 125I-labelled MT. The moAbs recognized MT but hardly recognized other analogues except for N-acetylserotonin with a crossreactivity of 0.81%. An inhibition curve for MT was obtained in the range of 50 pg to 100 ng and 1.4 ng of MT inhibited the value of the assay by half. There is interference from some unknown source in human serum. 相似文献
76.
77.
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
78.
Hiroshi Kunikane Hiroshi Ishikura Jun Yamaguchi Takashi Yoshiki Tetsuo Itoh Miki Aizawa 《Pathology international》1987,37(4):615-625
The clinicopathology of 13 cases of chondroid syringoma were examined. The ages of the patients ranged from 26 to 86 years, with an average of 48 years. There were eight males and five females. Ten tumors out of the thirteen appeared on the face. Only one patient out of ten was suspected of recurrence in follow-up information. Histologically, all tumors consisted of epithelial cells, chondroid or myxoid matrix, and other strumal elements. The tumors were histologically classified into two types; twelve tumors had tubular and cystic lumina lined by two layers of epithelial cells, and only one case had small lumina lined by only a single layer. By an immunohistochemical study with a PAP method, positive stainings of keratin were observed in all cases, and S-100 protein in all but one. Ultrastructurally, the tumor cells showed features of an epithelial cell. Some ultrastructural differences were noted between two types of chondroid syringoma. Type I tumor cells had many tonofilaments in cytoplasm, but cytoplasmic filaments in type II were of the intermediate-type. 相似文献
79.
Sharma R Bhatti S Gomez M Clark RM Murray C Ashizawa T Bidichandani SI 《Human molecular genetics》2002,11(18):2175-2187
Friedreich ataxia is commonly caused by large expansions of a GAA triplet-repeat (GAA-TR) sequence in the first intron of the FRDA gene. We used small-pool PCR to analyze somatic variability among 7190 individual FRDA molecules from peripheral blood DNA of subjects carrying 12 different expanded alleles, ranging in size from 241 to 1105 triplets. Expanded alleles showed a length-dependent increase in somatic variability, with mutation loads ranging from 47% to 78%. We noted a strong contraction bias among long alleles (>500 triplets), which showed a 4-fold higher frequency of large contractions versus expansions. Some contractions were very large; of all somatic mutations scored, approximately 5% involved contractions of >50% of the original allele length, and 0.29% involved complete reversion to the normal/premutation length (< or =60 triplets). These observations contrast sharply with the strong expansion bias seen in expanded CTG triplet repeats in myotonic dystrophy. No somatic variability was detected in >6000 individual FRDA molecules analyzed from 15 normal alleles (8-25 triplets). A premutation allele with 44 uninterrupted GAA repeats was found to be unstable, ranging in size from 6 to 113 triplets, thus establishing the threshold for somatic instability between 26 and 44 GAA triplets. Analysis of an additional 7850 FRDA molecules from serially passaged lymphoblastoid cell lines carrying nine expanded alleles (132-933 triplets) showed very low mutation loads, ranging from 0% to 6.2%. Our data indicate that expanded GAA-TR alleles in Friedreich ataxia are highly mutable and have a natural tendency to contract in vivo, and that these properties depend on multiple factors, including DNA sequence, triplet-repeat length and unknown cell-type-specific factors. 相似文献