全文获取类型
收费全文 | 7887篇 |
免费 | 318篇 |
国内免费 | 62篇 |
专业分类
耳鼻咽喉 | 50篇 |
儿科学 | 161篇 |
妇产科学 | 39篇 |
基础医学 | 1046篇 |
口腔科学 | 153篇 |
临床医学 | 379篇 |
内科学 | 2435篇 |
皮肤病学 | 54篇 |
神经病学 | 478篇 |
特种医学 | 280篇 |
外科学 | 1204篇 |
综合类 | 38篇 |
预防医学 | 205篇 |
眼科学 | 86篇 |
药学 | 547篇 |
中国医学 | 64篇 |
肿瘤学 | 1048篇 |
出版年
2023年 | 34篇 |
2022年 | 60篇 |
2021年 | 121篇 |
2020年 | 67篇 |
2019年 | 82篇 |
2018年 | 108篇 |
2017年 | 77篇 |
2016年 | 110篇 |
2015年 | 123篇 |
2014年 | 174篇 |
2013年 | 231篇 |
2012年 | 388篇 |
2011年 | 452篇 |
2010年 | 242篇 |
2009年 | 252篇 |
2008年 | 450篇 |
2007年 | 484篇 |
2006年 | 511篇 |
2005年 | 559篇 |
2004年 | 548篇 |
2003年 | 542篇 |
2002年 | 581篇 |
2001年 | 111篇 |
2000年 | 109篇 |
1999年 | 122篇 |
1998年 | 188篇 |
1997年 | 145篇 |
1996年 | 119篇 |
1995年 | 108篇 |
1994年 | 111篇 |
1993年 | 114篇 |
1992年 | 96篇 |
1991年 | 75篇 |
1990年 | 95篇 |
1989年 | 67篇 |
1988年 | 52篇 |
1987年 | 66篇 |
1986年 | 59篇 |
1985年 | 42篇 |
1984年 | 30篇 |
1983年 | 32篇 |
1982年 | 41篇 |
1981年 | 42篇 |
1980年 | 34篇 |
1979年 | 19篇 |
1978年 | 23篇 |
1977年 | 15篇 |
1976年 | 16篇 |
1973年 | 17篇 |
1970年 | 13篇 |
排序方式: 共有8267条查询结果,搜索用时 15 毫秒
111.
Yukie Niwa Tsuyoshi Sakane Masao Shingu M. Mitsuo Yokoyama 《Journal of clinical immunology》1983,3(3):228-240
Neutrophils from the synovial fluid (SFN) of 10 patients with active rheumatoid arthritis (RA) were investigated to determine the generation of oxygen intermediates (OI) (O2-, H2O2, OH .), chemiluminescence, and lysosomal enzymes (lysozyme and beta-glucuronidase). Lymphocytes from healthy individuals were cocultured at 37 degrees C for 17 hr with SFN from the patients and the number of OKT4+, OKT8+, and OKT3+ cells and the response to mitogens were determined. A markedly increased OI and slightly elevated lysosomal enzyme levels were observed in SFN from patients. Coculture of lymphocytes with SFN resulted in a decreased number of OKT4+ and OKT8+ cells and a greatly reduced response to Con A and mildly diminished response to PHA, while OKT3+ cells were not affected. The simultaneous addition of superoxide dismutase and catalase restored the impairment of monoclonal antibody reaction and lymphocyte responsiveness almost to control levels. It is suggested that the disturbed immunoreactivity of synovial fluid lymphocytes from RA patients may be due to increased OI generated by stimulated neutrophils. 相似文献
112.
Photodegradation behavior for copolymers of styrene (St), α-methyl styrene (α-MSt) and methyl methacrylate (MMA) with methyl vinyl ketone (MVK) and phenyl vinyl ketone (PVK) in the presence of air was investigated in the solid state and in solution. Photolysis of St/MVK and St/PVK copolymers proceeded smoothly and an increase of the ketone in the copolymer resulted in an increase of the rate of degradation. Generally, the rate of degradation is faster in St/PVK copolymers than in St/MVK copolymers. It is likely that the degradation of the copolymers takes place mainly through NORRISH type II reaction. It was found that the photolysis of α-MSt/PVK copolymers was retarded considerably as compared with St/PVK copolymers. An unexpected behavior was observed in the case of MMA/MVK or MMA/PVK copolymers. These copolymers were expected to degrade with slow rates; they degraded, however, rapidly. Some experiments were done to explain this phenomenon. 相似文献
113.
Yoshiharu Doi Masao Kunioka Akira Tamaki Yoshiyuki Nakamura Kazuo Soga 《Macromolecular chemistry and physics.》1988,189(5):1077-1086
Copolyesters of 3-hydroxybutyric acid (HB) and 3-hydroxyvaleric acid (HV), P(HB-co-HV), were isolated from Alcaligenes eutrophus and characterized by solution NMR, solid-state 13C CP/MAS NMR, and differential scanning calorimetry. The 13C CP/MAS NMR analysis was compatible with that of a random copolyester of oxy-(1-methyl-3-oxotrimethylene) ( B ) and oxy-(1-ethyl-3-oxotrimethylene) ( V ) units which adopts a regular conformation of a 21 -helix in the solid state throughout a wide range of compositions varying from 0 to 90 mol-% V units. The chain dynamics of P(HB-co-HV) in chloroform was studied by analysis of the 13C and 1H NMR spectra. The carbon-13 spin-lattice relaxation times (T1) and nuclear Overhauser enhancements (NOE) indicated that the copolyester molecules in chloroform are not rigid but rather flexible. The conformational preferences of the copolyester molecules were determined by analysis of the 1H NMR spectra. 相似文献
114.
Yoshihide Takaki Masao Kishikawa Ichiro Serine Issei Nishimori Mitsuro Hieata Hideo Namiki 《Pathology international》1983,33(4):823-829
Malignant fibrous histiocytoma (MFH) has become one of the most common malignancies occurring in soft tissue. To our knowledge, the present case is the first of MFH occurring in the endometrium. The uterus removed from a 47-year-old woman demonstrated a large multinodular endometrial lesion with gross invasive foci in the myometrium and the left oviduct. Microscopically, the endometrial tumor and the invasive lesions were composed of dense sheets of markedly pleomorphic cells consisting of fibroblast-like cells, histiocyte-like cells, foamy histiocytes, benign appearing multinucleated giant cells resembling either osteoclasts or Touton giant cells, and bizarre tumor giant cells. Some of the tumor cells showed phagocytic activities. The tumor cells were oriented in a random or haphazard fashion and classical storiform and fascicular patterns were not observed. The tumor was diagnosed as MFH consisting exclusively of so-called pleomorphic pattern. The patient is alive without evidence of disease, months following total hysterectomy and bilateral salpingo-oophorectomy. 相似文献
115.
Hoshina M Shibuya H Kubo HD Miura M Ohashi I Yoshimura R Oota S 《Medical physics》2004,31(7):2068-2074
A new characterization of depth-ionization parameters for electron beams is empirically deduced from our data analysis based on the divided difference method (the DD method), which employs the numerical differential of an ionization curve. The important feature of the present method is that it does not necessarily require normalized percent depth-ionization (NPDI) data. The depth of 50% of maximum ionization, I50, which is an important parameter for electron beam dosimetry, can be deduced from the analysis of an unnormalized (or partial) depth-ionization (UDI) curve obtained over a short interval of depth. The values of I50 determined by the DD method are in agreement to within 0.1 mm for energies of 4, 6, and 9 MeV, compared with the ones determined by the TG-51 protocol method (or the conventional method), and the difference was 0.9 mm for 12 and 15 MeV. The dose at the reference depth, dref, calculated from I50 by the DD method, is found to be in agreement with TG-51 to within 0.1%. The field size dependence of the DD method using UDI data was studied for three field sizes: 6 x 6, 10 x 10, and 20 x 20 cm2. For all energies, the discrepancies of I50 as determined by both methods were 0.9 mm on average for the 6 x 6 cm2 fields and 0.6 mm for the other two field sizes. This dependence was remarkable for 6 x 6 cm2 fields for 12 and 15 MeV, and the discrepancies shown by the DD method were 1.2 mm for 12 MeV and 1.8 mm for 15 MeV, respectively. Since the reference field size in clinical dosimetry is usually 10 x 10 cm2, this dependence will not affect clinical dosimetry. The DD method could be an alternative option for checking beam quality in dose calibration. 相似文献
116.
117.
Summary This short paper summarizes the basic concept and the technology of a new computed radiographic system which uses an energy-storage phosphorus panel called Imaging Plate as an image sensor. The Imaging Plate can be used to obtain radiographs in exactly the same way as the screen-film combination is used in conventional radiography. The system eliminates the drawbacks of conventional screen-film radiography by combining digital image processing and digitization of the x-ray energy pattern utilizing scanning laser stimulated luminescence.The major part of this paper was originally delivered at the 1984 AAPM Annual Summer School which was held on July 22–27 at University of Notre Dame, USA. Modified for the publication in the Neurosurgical Review. 相似文献
118.
To determine if clinically observed disorders in heme biosynthetic enzymes, known as sporadic porphyria cutanea tarda (PCT), could be reproduced in experimental animals, male Fischer rats were treated with ethanol, estrogen and hexachlorobenzene (HCB). A series of heme biosynthetic enzymes were assayed. In the rats given free access to 8% ethanol-drinking water for 15 weeks, -aminolevulinate (ALA) dehydratase was significantly reduced in erythrocytes. In the liver, ALA synthetase and uroporphyrinogen (UROgen) decarboxylase activities remained unchanged. In bone marrow cells, these activities did not change markedly. In the rats treated with estrogen (1 mg estrioltripropionate /rat/week, IM), no body weight gain was observed during the treatment for 15 weeks and urinary ALA excretion increased to 1.7 fold over normal level. In the liver, a significant increase was observed in the activity of ALA dehydratase, but other enzymes remained within the normal level. In bone marrow cells and erythrocytes, ALA dehydratase was also increased. ALA synthetase increased only in bone marrow cells to 2.1 times higher than the control level. In rats fed 0.3% HCB-diet for 8 weeks, urinary excretion of ALA, coproporphyrin and uroporphyrin increased to 2.4, 3.3 and 3.8 times higher than the controls, respectively. In the liver, an increase was observed in ALA synthetase, while a decrease was observed in ALA dehydratase and UROgen decarboxylase. In bone marrow cells and erythrocytes, ALA dehydratase was reduced and activities of other enzymes did not show any changes.These results indicate that alcohol, estrogen and HCB do not produce phenomena similar to those observed clinically in PCT. 相似文献
119.
Kiyoji Kimura Ryuzo Ohno Ichita Amaki Kenichi Hattori Yutaka Hirota Akira Hoshino Michito Ichimaru Munemoto Ito Ikuo Kimura Tadashi Maekawa Toru Masaoka Toru Nakamura Makoto Ogawa Masao Oguro Kazuo Ohta Shigeyuki Osamura Masanori Shimoyama Fumimaro Takaku Yoshiro Uzuka Kazumasa Yamada 《Medical oncology (Northwood, London, England)》1986,3(1):15-24
A phase I study ofN 4-behenoyl-1-β-d-arabinofuranosylcytosine (BHAC) was conducted in 66 patients, 41 with solid tumors and 25 with hematological malignancies. The patients received either a 2-h single intravenous (i.v.) drip infusion (Schedule 1) or consecutive daily 2-h i.v. infusions (Schedule 2). In Schedule 1 the daily dose was initiated with 1.5 mg kg?1 which was escalated up to 7 mg kg?1. Side-effects were mild, and included nausea, vomiting, epilation, and hot flushes. Because of the presence of the solvent vehicle, HCO-60 and in consideration of the mechanism of action of BHAC, the dose escalation was stopped at 7 mg kg?1. In Schedule 2, the daily dose was started with 1.5 mg kg?1 which was escalated up to 8 mg kg?1 and given for 2–16 days. Myelosuppression was found to be dose-limiting toxicity. The maximum tolerated dose (MTD) in patients with non-hematological solid tumors was assumed to be 5 mg kg?1 daily × 5 days. The plasma disappearance curve of BHAC looked biphasic, and when 4 mg kg?1 of BHAC were administered the half-lives of the initial phase (t 1/2α) and the second phase (t 1/2β) were calculated as 0.798 and 5.76 h respectively. In Schedule 2 complete remission was observed in 5 out of 21 patients with acute leukemia, one partial remission in Hodgkin’s disease, and one 1-B response (Karnofsky) in thyroid papillary adenocarcinoma. 相似文献
120.
The effect of calcium-balanced heparin (471896, CIBA CORNING) on blood gas and electrolyte analysis was evaluated, by comparing with that of sodium heparin (Na heparin). One ml of whole blood was collected into a syringe, which contained calcium-balance heparin (Ca balanced heparin) or Na heparin. 122 pairs of blood samples obtained from 15 patients were analyzed for Na, K, ionized calcium (Ca(++)), total hemoglobin, pH, P(CO)(2), and P(O)(2) by an automatic blood gas and electrolyte analyzer, CIBA CORNING model 288. There was a significant difference ( P < 0.05) in pH, P(CO)(2), Na, and Ca(++) between the two different groups. Ca(++) concentration was significantly less in Na heparin group than in Ca balanced heparin group, probably due to more chelation of Ca(++) by Na heparin than Ca balanced heparin. The present study suggests that the Ca balanced heparin has minimal effect on the blood gas and electrolyte analysis, and is a suitable anticoagulant for the Ca(++) measurement. 相似文献