全文获取类型
收费全文 | 6724篇 |
免费 | 349篇 |
国内免费 | 48篇 |
专业分类
耳鼻咽喉 | 38篇 |
儿科学 | 172篇 |
妇产科学 | 74篇 |
基础医学 | 930篇 |
口腔科学 | 101篇 |
临床医学 | 388篇 |
内科学 | 1851篇 |
皮肤病学 | 104篇 |
神经病学 | 555篇 |
特种医学 | 275篇 |
外科学 | 1134篇 |
综合类 | 24篇 |
预防医学 | 154篇 |
眼科学 | 153篇 |
药学 | 416篇 |
中国医学 | 25篇 |
肿瘤学 | 727篇 |
出版年
2023年 | 33篇 |
2022年 | 69篇 |
2021年 | 112篇 |
2020年 | 64篇 |
2019年 | 94篇 |
2018年 | 94篇 |
2017年 | 98篇 |
2016年 | 137篇 |
2015年 | 159篇 |
2014年 | 164篇 |
2013年 | 194篇 |
2012年 | 365篇 |
2011年 | 422篇 |
2010年 | 208篇 |
2009年 | 217篇 |
2008年 | 358篇 |
2007年 | 460篇 |
2006年 | 397篇 |
2005年 | 458篇 |
2004年 | 436篇 |
2003年 | 466篇 |
2002年 | 423篇 |
2001年 | 95篇 |
2000年 | 75篇 |
1999年 | 111篇 |
1998年 | 137篇 |
1997年 | 112篇 |
1996年 | 128篇 |
1995年 | 114篇 |
1994年 | 91篇 |
1993年 | 71篇 |
1992年 | 56篇 |
1991年 | 68篇 |
1990年 | 58篇 |
1989年 | 63篇 |
1988年 | 43篇 |
1987年 | 33篇 |
1986年 | 38篇 |
1985年 | 27篇 |
1984年 | 40篇 |
1983年 | 28篇 |
1982年 | 29篇 |
1981年 | 37篇 |
1980年 | 33篇 |
1979年 | 17篇 |
1978年 | 28篇 |
1977年 | 27篇 |
1976年 | 18篇 |
1975年 | 18篇 |
1974年 | 18篇 |
排序方式: 共有7121条查询结果,搜索用时 15 毫秒
91.
Yuki Kanda Dr. Koji Koike Yoshiki Sakamoto Yasuko Osako Kanji Masuhara Kazuyoshi Watanabe Susumu Tsurufuji Kenji Hirota Akira Miyake 《American journal of reproductive immunology (New York, N.Y. : 1989)》1997,38(1):33-38
PROBLEM: Human GRO-alpha (GRO-α) is a new member of the chemokine family that is supposed to play an important role in inflammatory and immune reactions. We established a sandwich enzyme-linked immunoassay (ELISA) system with polyclonal antibodies against human GRO-α and investigated the serum level of healthy donors to establish normal ranges for this chemokine in adults. METHODS: GRO-α concentrations were measured cross-sectionally in the sera of 240 healthy adults. The variability of serum GRO-α levels was also measured in normal volunteers, samples from whom were obtained by sequential venipunctures or by a small plastic cannula with a heparin-saline lock, to determine short-term variability. RESULTS: Whereas there was no difference between the concentration of human GRO-α from men (logarithmic mean, 77.6 pg/ml, n = 120) and that from women with normal menstrual cycles (log mean, 71.6 pg/ml, n = 73), the concentration from postmenopausal women (log mean 45.0 pg/ml, n = 31) was lower than that from women with normal menstrual cycles (log mean 71.6 pg/ml, n = 73). However, we could not detect any significant difference between healthy donors' serum levels and those of donors with acute inflammation. Fewer variations were recognized in the case of the sequential venipunctures method than in that of the heparin-saline lock method. CONCLUSION: We found that the GRO-α concentration of postmenopausal women was significantly lower than that of women with normal menstrual cycles. These results suggest the GRO-α serum levels of normal healthy women may have some correlation with sex hormones. 相似文献
92.
Yasuhiro Amemiya Masamichi Katayama Susumu Harada 《Macromolecular chemistry and physics.》1977,178(2):289-315
Copolymers of sulfur dioxide with N-substituted 4-(1,6-heptadiene-4-yl)pyridinium chlorides and bromides ( 1 ) and N-substituted 4-(3-butenyl)pyridinium chlorides and bromides, and some other 1,6-heptadiene derivatives 3 substituted in 4-position were prepared. The effects of the copolymerization conditions on the conversions and viscosities of the copolymers were studied and their structures by elemental analyses, IR and 1H NMR spectroscopy. The thermal stabilities of the copolymers were also examined. 相似文献
93.
Okamura A Yazawa S Nishimura T Tanaka S Takai I Kudo S Asao T Kuwano H Matta KL Akamatsu S Kochibe N 《Clinical & experimental metastasis》2000,18(1):37-43
A new ex vivo method for assaying adhesion of cancer cells to the greater omentum has been developed using mouse greater omentum and [3H]labelled human gastric and mouse colorectal cancer cells. Since the adhesion rates were found to increase up to 18 h and labelled cells seemed to be stable during the period, the present method could be useful for investigating adhesion of cancer cells to the greater omentum, which must occur at the first step of the peritoneal dissemination. The adhesion of cancer cells to the greater omentum was inhibited by a series of chemically synthesized oligosaccharides and Galβ1,3[3OMeGalβ1,4GlcNAcβ1,6]αBn was found to be the best inhibitor. The anti-tumor effect of this novel tetrasaccharide in vivo was shown in preliminary experiments using Balb/c mice and colon26 cells. 相似文献
94.
Hyodo T Kanazawa S Dendo S Kobayashi K Hayashi H Kouno Y Fujishima M Hiraki Y 《Acta medica Okayama》2004,58(5):235-240
We compared the thin-section CT findings of 11 intrapulmonary lymph nodes with pathological findings and evaluated the possibility of CT scan differential diagnosis from pulmonary metastatic nodules. First, we retrospectively reviewed CT scan and pathological findings of intrapulmonary lymph nodes. The median size of these nodules was 6.2 mm. The nodules appeared round (n=3) or angular (n=8) in shape with a sharp border, and they were found below the level of the carina. The median distance from the nearest pleural surface was 4.6 mm, and 3 of the 11 nodules were attached to the pleura. On thin-section CT scan, linear densities extending from the intrapulmonary lymph nodes were frequently visualized, and were pathologically proven to be ectatic lymphoid channels. We then compared the thin-section CT findings of 8 metastatic nodules less than 1 cm in diameter with those of the 11 intrapulmonary lymph nodes. The median size of these nodules was 6.8 mm, and the median distance from the nearest pleural surface was 16 mm. All nodules appeared round in shape. None of the nodules had linear densities extending from the nodules. The linear densities on thin-section CT scan may be the most useful characteristic of intrapulmonary lymph nodes, when differential diagnosis from metastatic nodules is necessary. 相似文献
95.
Masanori Hara Daisuke Mase Susumu Inaba Akira Higuchi Takakuni Tanizawa Noriaki Yamanaka Yuichi Sugisaki Yoshikazu Sado Toshio Okada 《Virchows Archiv : an international journal of pathology》1986,408(4):403-419
Summary The immunofluorescent localization of glomerular basement membrane (GBM) antigens was examined in 52 specimens from normal kidneys and in various renal diseases using antisera to human GBM HGBM), IV type collagen (IV Col) and P3 antigen, a rat nephritogen. Anti-HGBM serum normally stained the GBM and the mesangium in a restrictive pattern, anti-IV Col serum stained the GBM and the mesangium in a wider pattern and anti-P3 serum stained only the GBM. In mesangial proliferative glomerulonephritis, including IgA nephropathy pathy and Henoch-Schönlein nephritis, the widened mesangial areas were stained with anti-HGBM and anti-IV Col sera. In membranous nephropathy, the punched-out lesions of thickened GBM were demonstrated with the three antisera in moderate cases and a double linear distribution with fine granulation with anti-HGBM and anti-IV Col sera were revealed in one severe case. In membranoproliferative glomerulonephritis, the expanded mesangium and thickened capillary walls were stained with anti-HGBM and anti-IV Col sera, while the outer line of glomerular capillary walls was only positive with anti-P3 serum. In crescentic glomerulonephritis, the collapsed glomerular tufts were stained normally with anti-HGBM and anti-P3 sera and weakly with anti-IV Col serum. In diabetic nephropathy, anti-HGBM serum stained the GBM in a double linear distribution without reacting with the expanded mesangium; anti-IV Col serum stained the mesangium and the GBM in a less clear double linear fashion while anti-P3 serum stained the GBM as single line. Thin membrane disease and Alport's syndrome had normal reactivity with all antisera. However, in one case of Alport's syndrome anti-HGBM and anti-P3 sera stained the GBM in a focal and segmental pattern, while normal staining with anti-IV Col serum was found. In lesions with adhesions and crescents the staining was positive for HGBM and IV Col and negative for P3; obsolescent glomeruli were stained with anti-HGBM and anti-P3 sera, and had diminished staining with anti-IV Col serum.The identification of the various structural glomerular antigens is useful in the classification of certain types of glomerular diseases. Further insight into the mechanisms underlying these conditions may be obtained in this way. 相似文献
96.
97.
AIMS: To elucidate the pathogenesis of the anal fibroepithelial polyp, we examined surgically resected lesions histopathologically. METHODS AND RESULTS: Twenty-seven surgically resected anal fibroepithelial polyps were investigated histologically with an additional immunohistochemical examination using anti-CD34. For a control study, the surgical specimens of the anal canal showing non-polypoid lesions, obtained from haemorrhoidectomy (18 specimens) and rectectomy (five specimens) due to rectal cancer without anal canal involvement, were also analysed. We demonstrated characteristic spindle or stellate cells immunohistochemically positive for CD34 in the anal fibroepithelial polyps (24/27, 89%). The number of CD34+ cells was statistically related to the size of anal fibroepithelial polyps, although CD34+ stromal cells were recognized in the non-polypoid anal submucosa and haemorrhoids. We also found hyalinized vascular changes in the base of six anal fibroepithelial polyps examined. These features were not detected in the non-polypoid anal canal. CONCLUSIONS: An increase in CD34+ stromal cells may play a role in the enlargement of anal fibroepithelial polyps. CD34+ stromal cells are suggested to be distinctive mesenchymal cells with a capability for tissue repair and overgrowth. The vascular impairment could be secondary change associated with localized tissue damage by abnormal traction. 相似文献
98.
Junji Furukawa Jitsuo Kiji Hisatoshi Konishi Kazuyoshi Yamamoto Shin-Ichi Mitani Susumu Yoshikawa 《Macromolecular chemistry and physics.》1973,174(1):65-71
The behavior of hydridonickel coordination compounds as catalysts for the oligomerization and polymerization of butadiene in various solvents was studied. In the presence of alcohol bis(tricyclohexylphosphine)chlorohydridonickel ( 4 , X = Cl) (HNiCl[P(C6H11)3]2) catalyzes the linear dimerization. With hydridotetrakis(phosphite)nickel(1+) ( 2 ) ([HNi{P(OR)3}4]+), which is prepared from tetrakis(phosphite)nickel ( 1 ) (Ni[P(OR)3]4) and trifluoroacetic acid, dimerization occurs in sec-alcohol but there is no reaction in tert-alcohol. The main product is 2-methylenevinylcyclopentane ( 8 ). The other products are 4-vinylcyclohexene ( 10 ), 1,5-cyclooctadiene ( 5 ), 1,3,7-octatriene ( 7 ) and 1,3,6-octatriene ( 9 ). The hydridonickel coordination compound, prepared with inorganic acids, does not afford the dimers but the 1,4-trans polymer. 相似文献
99.
Induction of neutrophil infiltration by rat chemotactic cytokine (CINC) and its inhibition by dexamethasone in rats 总被引:4,自引:0,他引:4
Noriyasu Hirasawa Masako Watanabe Suetsugu Mue Kazuyoshi Watanabe Susumu Tsurufuji Kazuo Ohuchi 《Inflammation》1992,16(2):187-196
In vivo effects of cytokine-induced neutrophil chemotactic factor (CINC) derived from rats on neutrophil infiltration were investigated using an air-pouch-type inflammation model in rats, and effects of dexamethasone on neutrophil infiltration induced by CINC was also examined in order to gain further insight into the mechanism of antiinflammutory activity of glucocorticoids. Injection of CINC into the air pouch made on the dorsum of rats induced a marked infiltration of neutrophils into the pouch fluid but not mononuclear cells and eosinophils during a 30-min interval after the injection. Maximum effect was induced at a dose of 1.4g/pouch. Treatment with dexamethasone 3 h before the injection of CINC suppressed the neutrophil infiltration in a dose-dependent manner, but no complete inhibition was observed. CINC injection into the air pouch of rats that had been sacrificed by bleeding in order to minimize neutroph il infiltration from blood stream also stimulated neutrophil infiltration into the pouch fluid when the carcass was incubated at 37C for 30 min, but the number of infiltrated neutrophils was about 35% of CINC-induced neutrophil infiltration in intact ruts. CINC-induced neutrophil infiltration in the carcass, which is supposed to be a reflection of neutrophil migration from extravascular space in subcutaneous tissues to pouch fluid, was not inhibited by dexamethasone treatment. Therefore, the inhibition of neutrophil infiltration by dexamethasone might be due to inhibition of the extravasation of peripheral neutrophils but not due to inhibition of neutrophil chemotaxis from subcutaneous extravascular space to pouch fluid. These findings suggest that clinical effects of steroidal antiinflammatory drugs on neutrophil infiltration in inflammatory disease is partly due to inhibition of neutrophil extravasation induced by preformed neutrophil chemotactic factors in the inflammatory site. 相似文献
100.
Effects of succinylated concanavalin A on infectivity and syncytial formation of human immunodeficiency virus 总被引:3,自引:0,他引:3
Toshio Matsui Susumu Kobayashi Osamu Yoshida Shin-ichi Ishii Yukichi Abe Naoki Yamamoto 《Medical microbiology and immunology》1990,179(5):225-235
The effects of various lectins on the infectivity of human immunodeficiency virus (HIV) type 1 was investigated. Among the 25 lectins investigated, 2 types of concanavalin A (Con A) and 3 types of phytohemagglutinin were found to inhibit HIV infection. Succinylated Con A (S-Con A) efficiently blocked HIV-induced formation of syncytia in a coculture of MOLT-4 cells and blocked cell-free infection by HIV of MT-4 cells. The HIV-binding study revealed that S-Con A only partially inhibited viral binding to cells, although the control Leu-3a monoclonal antibody strongly inhibited it. When S-Con A was added to cultures after the initiation of viral adsorption, the number of HIV antigen-positive cells that developed depended on the time interval before addition of the compound. S-Con A inhibited HIV infection even after viral binding to cells at 0 °C and further incubation at 37 °C for 1 day. These data suggest that S-Con A inhibited mainly the fusion process rather than viral binding to cells in exerting its anti-HIV activity. 相似文献