首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   39743篇
  免费   1971篇
  国内免费   192篇
耳鼻咽喉   308篇
儿科学   724篇
妇产科学   633篇
基础医学   5048篇
口腔科学   1005篇
临床医学   2629篇
内科学   9680篇
皮肤病学   603篇
神经病学   2834篇
特种医学   1424篇
外科学   7685篇
综合类   178篇
预防医学   1313篇
眼科学   454篇
药学   2867篇
中国医学   130篇
肿瘤学   4391篇
  2023年   177篇
  2022年   171篇
  2021年   690篇
  2020年   419篇
  2019年   555篇
  2018年   695篇
  2017年   545篇
  2016年   626篇
  2015年   713篇
  2014年   947篇
  2013年   1089篇
  2012年   1706篇
  2011年   1848篇
  2010年   1039篇
  2009年   839篇
  2008年   1607篇
  2007年   1696篇
  2006年   1697篇
  2005年   1759篇
  2004年   1787篇
  2003年   1713篇
  2002年   1711篇
  2001年   1683篇
  2000年   1632篇
  1999年   1554篇
  1998年   559篇
  1997年   446篇
  1996年   396篇
  1995年   355篇
  1994年   339篇
  1993年   303篇
  1992年   1012篇
  1991年   949篇
  1990年   822篇
  1989年   926篇
  1988年   789篇
  1987年   718篇
  1986年   761篇
  1985年   689篇
  1984年   439篇
  1983年   381篇
  1982年   192篇
  1981年   183篇
  1979年   313篇
  1978年   239篇
  1977年   209篇
  1975年   211篇
  1974年   189篇
  1973年   175篇
  1971年   177篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
93.
Alexia with agraphia is very rare symptom in multiple sclerosis. We present a patient of opticospinal multiple sclerosis with kanji-predominant alexia with agraphia. A 55-year-old, right-handed man was admitted to our hospital because of difficulty in reading and writing in August 2001. The patient had been diagnosed as having relapsing-remitting opticospinal multiple sclerosis eight years prior to admission. Language examination showed alexia with agraphia predominantly affecting kanji and also mild naming difficulties, but a good comprehension and a normal repetition. T2-weighted MRI demonstrated hyperintensity area in the left temporo-parietal lobe, involving the white matter beneath the postero-inferior temporal lobe and inferior parietal lobule. On brain SPECT, low blood perfusion was observed in the left temporo-parietal regions. Although agraphia for kana and alexia for both kana and kanji improved after steroid therapy, agraphia for kanji did not improve. After the treatment, high intensity area of inferior parietal lobule was disappeared on MRI, and the hypoperfusion of inferior parietal lobule on brain SPECT was also improved, but the lesion of left postero-inferior temporal lobe did not show any remarkable changes. We considered that the kanji-predominant alexia with agraphia was due to the lesions of left inferior parietal lobule and postero-inferior temporal lobe, and agraphia for kanji was due to the lesion of left postero-inferior temporal lobe.  相似文献   
94.
We report on a male patient with Pick disease who had shown severe white matter atrophy and dilatation of the lateral ventricle in the frontal lobe from an early stage. Upon admission to our hospital 2 years after disease onset, the patient showed apathy, and MRI revealed severe atrophy of the cortex and white matter of the frontal lobe. He died at age 74, 11 years after disease onset. Autopsy revealed severe atrophy of the frontal and temporal lobes, severe loss of white matter in the frontal lobe, dilatation of the lateral ventricles, and cortical thinning. Histopathological examination showed severe loss of myelinated fibers in the frontal white matter and severe neuronal loss with gliosis in the frontal and temporal cortices. Many Pick bodies were seen. Our patient had a rare case of Pick disease predominantly affecting the frontal lobe with severe involvement of the white matter from an early stage. This case suggests that myelinated fibers in the white matter as well as cerebral neurons are primarily affected in Pick disease.  相似文献   
95.
We reported a case of X-linked lymphoproliferative syndrome (XLP) with multiple nodular lesions in the brain and lungs. A 21-year-old man was admitted because of one month history of low grade fever, headache, nausea, and amnesia. He developed agammaglobulinemia following Epstein-Barr virus infection at 3-year-old, and thereafter was administered 7.5g of immunoglobulin every 3 weeks with a diagnosis of XLP. Physical examination was unremarkable on admission. Neurological examination revealed disorientation of time, and bilateral gaze-evoked nystagmus. Neuropsychological tests demonstrated impairment of recent memory and calculation. Pleocytosis (83/microl) and increase of protein (1269 mg/dl) and IgG (141 mg/dl) in the CSF were observed. Brain MRI showed multiple nodular lesions with high intense signal on T2-weighted images and Gd-DTPA enhancement on T1-weighted images. Chest CT showed multiple nodular lesions in the bilateral lungs. The needle lung biopsy was performed, which showed infiltration of lymphocytes around the vessels. An immunohistochemical study showed that the infiltrating cells were mainly CD8 positive T lymphocytes. B lymphocyte and plasma cells were not seen. The histological findings excluded intravascular malignant lymphoma and lymphomatoid granulomatosis. Therefore we diagnosed lymphoid vasculitis. The patient developed pancytopenia caused by hemophagocytic syndrome 48 days after admission and was treated with 1 g of methylprednisolone per day for 3 days and a tapered dose of steroid (500 mg to 125 mg of methylprednisolone and 60 mg to 10mg of predonisolone) for 21 days, which resulted in the improvement of clinical features (hemophagocytic syndrome and central nervous system symptoms) and the abnormal CSF findings. The multple nodular lesions in the brain and the lungs shrank 1 month after treatment and disappeared 11 months later. There are few reports concerning lymphoid vasculitis with XLP, and no effective treatment has been described. Our case suggests that steroid therapy may be useful for the treatment of lymphoid vasculitis in XLP.  相似文献   
96.
The effectiveness of various oxygen carrying treatments in sensitizing subpopulations of the FSallC fibrosarcoma to low doses of radiation was assessed, and compared with survivals obtained with the same cells after in vivo irradiation under normally oxygenated or hypoxic conditions. FSallC tumors were treated with 2-10 Gray then the Hoechst 33342 dye diffusion method was used to separate the tumor into bright (enriched in normally oxygenated cells) and dim (enriched in hypoxic cells) subpopulations. There was good agreement between the survival of normally oxygenated cells in culture and bright cells from tumors and between hypoxic cells in culture and dim cells from tumors over a radiation dosage range of 2-5 Gray. At 10 Gray bright cells from tumors were minimally less sensitive to the radiation dose than normally oxygenated cells in vivo. When maximally effective doses of perfluorochemical emulsions (F44E at 4 g PFC/kg or Fluosol-DA at 2.4 g PFC/kg) or a purified bovine hemoglobin solution (PBHS at 1.32 g protein/kg) were administered 1 hr. prior to radiation therapy with carbogen (95% O2, 5% CO2) breathing prior to and during radiation delivery, low single doses of x-ray (2-5 Gray) were measurably more cytotoxic toward both FSallC tumor cell subpopulations. These results indicate that perfluorochemical emulsions or purified bovine hemoglobin preparations along with carbogen breathing may be able to increase tumor radiosensitivity to the relatively low radiation doses per fraction used in the clinic.  相似文献   
97.
Distortion and movement of the expander during skin expansion.   总被引:2,自引:0,他引:2  
Distortion and movement of tissue expanders can cause expansion of the wrong area, such as the naevus or the scar that is to be resected. In 71 rectangular expanders, we examined the incidence of distortion (over 15 degrees) and movement (over 3 cm). We divided the expanders into three anatomical site groups: scalp, body, and extremities, and compared the complication rate between two study groups (distortion or movement, or not). In total, the incidence of distortion was 15/71 (21%) and that of movement 5/71 (7%). Distortion occurred mainly in the extremities (11/33,33%). The implanted expanders tended to move more often in the body part (3/15, 20%). In the extremities, the bigger the angle between the axis of the implanted expander and that of the extremity, the bigger the angle of distortion. Although the incidence of complications between the two groups was not significant, except for alteration in design of the flap, we recommend that these points should be considered when preoperative plans are being made for appropriate patients.  相似文献   
98.
Employing HPLC fluorometry, gas-liquid chromatography (GLC) and a novel enzymelinked immunosorbent assay (ELISA) based on a monoclonal antibody, 40 corn samples, each collected in 1993 from agricultural stocks for human consumption in Haimen (Jiangsu County) and Penlai (Shandong Province), high- and low-risk areas for primary liver cancer (PLC) in China, respectively, were analysed for fumonisins (FBs), aflatoxins (AFs) and trichothecenes. Levels and positive rates of FBs and deoxynivalenol (DON) were significantly higher in Haimen than in Penlai. ELISA of the 40 corn samples harvested in the two areas in 1994 revealed that FB contamination levels and rates in these areas were comparable to those observed in 1993 in Haimen. ELISA analysis of 1993 and 1994 products revealed a wide occurrence of AFB1 but the positive rates as well as levels were not significantly different between these areas. ELISA of the same sample number of corn harvested in 1995 revealed that FB contamination in Haimen was significantly higher than in Penlai. These 3-yearly surveys of corn samples (240 in total) demonstrated that corn harvested in Haimen was highly contaminated with FBs and that the contamination level, as well as positive rate in 1993 and 1995, were 10–50-fold higher than those in Penlai, suggesting FBs as a risk factor for promotion of PLC in endemic areas, along with the trichothecene DON. Co-contamination with AFs, potent hepatocarcinogens, was assumed to play an important role in the initiation of hepatocarcinogenesis.  相似文献   
99.
Skin tumors were produced on the back of hairless mice, HOS (HR/De), by exposure to ultraviolet B light (UVB, 290–320 nm) with 4 different protocols. The first tumors appeared earlier (in 10 weeks in group I and 7 weeks in group III) when initial intense exposure was given, followed by repeated lower-level exposures, than when the mice were exposed to the repeated UV only (in 16 weeks both in group II and group IV). All mice developed skin tumors earlier in the groups given the repeated UV exposures three times a week than in the groups given the exposures twice a week. Most of the skin tumors produced by the UVB exposure were histologically malignant, being transplantable to nude mice, and the cultured cells grown from the tumors were capable of producing tumors when injected into nude mice. The accelerated development of skin tumors by initial intense exposure and short intervals of repeated exposure observed in this study may have implications for humans who expose themselves to intense sunbathing and UV tanning (burning) by fluorescent sun lamps.  相似文献   
100.
Y Matsuki  K Suzuki  M Hara  A Kitani  T Hirose  M Harigai  M Kawakami  N Tanaka  M Kawagoe  H Nakamura 《Ryūmachi》1992,32(2):154-9; discussion 159-62
Arterial thrombosis is one of the major symptoms of antiphospholipid syndrome (APS). However, thrombosis in a primary branch of the aorta has rarely been reported in APS. We report here a case of APS complicated by thromboses in both the left subclavian artery and the left external iliac vein. A 32-year-old woman was admitted in May, 1990 complaining of no pulse in the left superficial arteries (e.g., left radial artery) for the past 5 years and acute swelling of the left lower extremity. A left ascending phlebography showed an occlusion of the external iliac vein and arteriography revealed obstruction in the left subclavian artery. Collateral circulations were developed at the site of each thrombus. Clotting and immunological studies revealed a prolonged APTT, a high titer of anticardiolipin antibody and lupus anticoagulant positive. We ruled out various diseases and clinical risk factors predisposing to both arterial and venous thromboses. Accordingly, we concluded that both thromboses were based on APS. Following treatment with anticoagulants, aspirin and corticosteroid, the swelling of her left thigh was diminished and the antibody titer was decreased within 3 months.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号