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   321篇
  免费   14篇
  国内免费   4篇
儿科学   4篇
妇产科学   2篇
基础医学   33篇
口腔科学   3篇
临床医学   22篇
内科学   73篇
皮肤病学   2篇
神经病学   2篇
特种医学   86篇
外科学   16篇
综合类   22篇
预防医学   15篇
眼科学   9篇
药学   10篇
中国医学   5篇
肿瘤学   35篇
  2022年   2篇
  2020年   2篇
  2018年   1篇
  2015年   5篇
  2014年   8篇
  2013年   13篇
  2012年   16篇
  2011年   17篇
  2010年   15篇
  2009年   19篇
  2008年   13篇
  2007年   7篇
  2006年   11篇
  2005年   6篇
  2004年   3篇
  2003年   5篇
  2002年   6篇
  2001年   5篇
  2000年   4篇
  1999年   6篇
  1998年   14篇
  1997年   15篇
  1996年   17篇
  1995年   14篇
  1994年   8篇
  1993年   12篇
  1992年   5篇
  1991年   2篇
  1990年   4篇
  1989年   9篇
  1988年   10篇
  1987年   7篇
  1986年   7篇
  1985年   9篇
  1984年   4篇
  1983年   5篇
  1982年   8篇
  1981年   6篇
  1980年   3篇
  1979年   1篇
  1978年   3篇
  1977年   7篇
  1976年   2篇
  1975年   2篇
  1968年   1篇
排序方式: 共有339条查询结果,搜索用时 0 毫秒
81.

BACKGROUND:

Fine‐needle aspiration (FNA) cytology is increasingly being used as a diagnostic modality for soft tissue and bone lesions. These diagnoses can be challenging because of a variety of factors, including interpretation and sampling issues. This study investigates the diagnostic utility of FNA biopsy, in addition to the diagnostic pitfalls, in soft tissue and bone cytopathology.

METHODS:

We retrospectively reviewed the soft tissue and bone FNAs over a 4‐year period (2004‐2008), along with available ancillary studies, pathological follow‐up, and clinical data. The cases with a cytologic‐histologic discrepancy were then reviewed.

RESULTS:

A total of 1114 soft tissue and bone FNAs were identified. Of the 1114 aspirates, 525 (47%) were positive for malignant cells, 505 (45.5%) were benign aspirates (including 189 benign lesions/neoplasms), 37 (3.5%) were inadequate, 34 (3%) had atypical cells, and 13 (1%) were suspicious for malignancy. Of the 586 cases (53%) with follow‐up, including 445 cases with histological follow‐up and 141 with ancillary studies, the overall sensitivity was 96%, the specificity was 98%, the positive predictive value was 99%, and the negative predictive value was 92%. A total of 15 false negatives and 3 false positives were identified with errors because of sampling (9 cases), interpretation (7 cases), and screening (2 cases).

CONCLUSIONS:

This large series demonstrates that there can be a high sensitivity and specificity in diagnosing bone and soft tissue lesions by FNA. Our data supports prior studies in the literature in showing that FNA cytology can be a valuable method for diagnosing these lesions. Cancer (Cancer Cytopathol) 2010. © 2010 American Cancer Society.  相似文献   
82.
彭颗红  薛敏  赵群 《中国妇幼保健》2011,26(8):1150-1152
目的:探讨多囊卵巢综合征(PCOS)患者血浆内脂素水平的变化及意义。方法:采用酶联免疫吸附法测定50例PCOS患者和45例健康体检者血浆内脂素水平,采用化学发光法测定空腹胰岛素(FINS)和血清性激素水平,采用葡萄糖氧化酶法测定空腹血糖(FPG)水平,并分析血浆内脂素水平与体重指数(BMI)、腰臀比(WHR)、空腹血糖、空腹胰岛素、胰岛素抵抗指数(HOMA-IR)和血清性激素的关系。结果:①PCOS组血浆内脂素水平为(21.18±4.31)ng/ml,对照组为(12.47±3.38)ng/ml,两组相比有统计学差异(P<0.01);肥胖PCOS组血浆内脂素水平为(22.10±5.20)ng/ml,非肥胖P-COS组为(20.39±3.27)ng/ml,分别高于肥胖对照组(14.68±3.02)ng/ml及非肥胖对照组(10.71±2.53)ng/mL(P<0.01)。②相关性分析显示,PCOS组血浆内脂素水平与WHR(r=0.43,P<0.01)、HOMA-IR(r=0.55,P<0.01)呈正相关。结论:PCOS患者血浆内脂素水平升高;血浆内脂素水平与胰岛素抵抗、肥胖呈正相关。  相似文献   
83.
Spontaneous mutation rates at the hypoxanthine-guanine phosphoribosyl transferase (hprt) locus were measured in human cancer cell lines defective in the mismatch repair (MMR) genes hMLH1, hPMS2, or GTBP, as well as in a cell line carrying mutations in both hMLH1 and hPMS2. The mutation rate was determined by quantitating mutant frequency increases within a single culture as a function of cell division. These MMR- deficient cell lines exhibited a 50- to 750-fold increase in mutation rate relative to a MMR-proficient cancer cell line. From lowest to highest, the spontaneous mutation rates relative to the MMR-gene defects studied here are as follows: hMLH1- < GTBP- < hPMS2- < hMLH1- / hPMS2-. In addition, a cell line in which MMR was restored by chromosome transfer exhibited a mutation rate 12-fold below the MMR- deficient parental cell line. These data support the notion that MMR plays an important role in controlling the rate of spontaneous mutation and suggest that different MMR-gene defects may vary in their ability to repair different types of DNA mismatches, thus leading to measurable quantitative differences in spontaneous mutagenesis. Furthermore, a difference in mutation rates was observed between a hPMS2-defective cell line (3.1 x 10(-5) mutations/cell/generation) and two hMLH1- defective cell lines (4.0 x 10(-6) and 7.3 x 10(-6) mutations/cell/generation). Assuming the hPMS2- and hMLH1-gene products only function in the proposed hMutL alpha heterodimer, then defects in either gene should yield comparable mutation rates. These data suggest that hPMS2 plays a critical role in MMR, while additional hMLH1 homologues or hPMS2 alone may function to partially complement defects in hMLH1.   相似文献   
84.
As a result of an appeal for a bone marrow donor for a North American Indian (Native American) patient, 261 Native Americans from our community were typed for HLA-A,B,DR antigens, and 51 were typed for HLA-A,B antigens only. The HLA antigen frequencies of the Native Americans were compared with those of 12,881 white bone marrow donors and were found to differ markedly. To investigate the implications these differences in HLA antigen frequencies would have for the location of unrelated bone marrow donors, the HLA types of 12 Native American bone marrow transplant patients from our institution were used to search among 5389 HLA-A,B,DR-typed white donors in the National Marrow Donor Program file and the file of 261 HLA-A,B,DR-typed Native American donors. In the white donor file, at least two donors were found that matched at all HLA-A,B,DR antigen loci of one Native American patient (8%). Using the Native American donor file, which was less than one-twentieth the size of the white donor file, and HLA-A,B,DR-matched donor was also found for one (8%) of the patients. These results suggest that although donors for nonwhites can be identified in a file of HLA-typed white volunteers, the probability of finding a suitably matched donor for such individuals is enhanced if donors representing racial or ethnic minorities are included in unrelated donor registries.  相似文献   
85.
目的了解各级临床实验室开展HIV血清学筛查试验的情况。方法采用问卷调查方式对141家临床艾滋病检测筛查实验室进行调查,利用Excel表建立数据库并进行分析。结果141家实验室2006年度共检测样本303045份,筛查阳性样本2404份,确认阳性样本276份,筛查阳性检出率和确认符合率分别为0.09%和11.48%。送检样本最多的科室是外、内、急诊和妇儿科。多数实验室采用国产酶联免疫吸附试剂。多数实验室缺少生物安全防护设备。结论进一步加强对实验室的管理,提高检测质量。  相似文献   
86.
87.
The objective was to explore the role of HLA-DRB1 genes in determining disease severity in rheumatoid arthritis (RA). The population comprised extended pedigrees of 17 multicase RA families. Family members were genotyped for both HLA-DRB1 alleles using restriction fragment length polymorphism (RFLP). Identification of HLA-DRB1*04 variants was performed using the Multiplex ARMS-RFLP technique. Compound heterozygote individuals carrying two different alleles containing the shared epitope (SE) were at greatest risk of developing RA (odds ratio = 36, 95% CI 9.1-143). A synergistic or additive effect of these alleles is suggested. Individuals carrying no SE alleles expressed milder disease, as measured by the Spread Severity (SS) index, compared to compound heterozygotes (P = 0.045). Compound heterozygosity was not invariably associated with severe disease with six (50%) having clinically mild disease at a median age of 57.5 yr and median disease duration of 16 yr. Inheriting two different SE-bearing alleles results in an increased risk of RA and, on average, greater disease severity. This is not, however, invariably associated with severe disease, making it of limited use as a predictor of prognosis.   相似文献   
88.
Fluorescence in situ hybridization (FISH) is a powerful tool for detection of numerical and structural chromosomal aberrations. We have compared conventional banding techniques and FISH for the detection of monosomy 7 (-7) and trisomy 8 (+8) in 89 patients with myeloid malignancies. Of these patients, 21 had -7, 30 had +8, four had both, and 34 had no aberrations or aberrations other than -7 or +8 as assessed by banding techniques. Sequential samples were available in 23 patients. Alphoid DNA probes specific for chromosomes no. 7 and 8 were used for FISH. As controls, 10 normal bone marrow (BM) samples were hybridized with the chromosomes no. 7 and 8 probes, and in addition all tumor samples were hybridized with a chromosome no. 1 specific probe. The cut-off value for -7 was 18% one-spot cells, and for +8 was 3% three-spot cells. FISH analysis of 44 samples with -7 or +8, and at least 10 metaphases evaluated, showed that the proportions of aberrant metaphase cells mirrored the interphase clone sizes. Most samples with nonclonal metaphase aberrations, including those with only a few metaphases, had increased numbers of aberrant interphase cells: 20% to 80% for -7, and 3% to 43% for +8. Interphase cytogenetics of the 34 samples without -7 or +8 did not show significant cell populations with -7 or +8. In four patients, -7 or +8 could not be confirmed by FISH due to additional structural aberrations, marker chromosomes, or wrongly interpreted banding results. As FISH will be used more and more in cytogenetic diagnosis, clinical follow-up, and therapy monitoring, it will be necessary to standardize FISH procedures and supplement the Standing Committee on Human Cytogenetic Nomenclature (ISCN) definitions of a clone with criteria specifically for in situ hybridization.  相似文献   
89.
A 29-yr-old white female has suffered from recurrent venous thromboses over the last 12 yr. Plasma antithrombin III (AT-III) levels were 48% of normal by immunoelectrophoresis and 56% by chromogenic assay. Three of four siblings and the father had similar AT-III levels without associated venous thromboses. Heparin-Sepharose chromatography demonstrated normal behavior of the patient's AT-III. Her purified AT- III could not be distinguished from AT-III purified from a normal control either by SDS polyacrylamide gel electrophoresis or by crossed immunoelectrophoresis, and the heparin cofactor activity and the progressive antithrombin activity of both AT-III samples were identical. Turnover studies were made in the patient using her own purified AT-III labeled with 131I, (*I). The results did not differ significantly from studies made with autologous *I-AT-III in two normal control women. Her fractional breakdown rate of 0.54 total plasma AT- III per day compared with 0.45 and 0.52 in the controls. These studies indicate that the patient synthesizes a normal AT-III molecule at half normal rates.  相似文献   
90.
Folylpolyglutamate synthetase (FPGS) is responsible for the metabolism of natural folates and a broad range of folate antagonists to polyglutamate derivatives. Recent studies indicated increased accumulation of methotrexate (MTX) polyglutamates (MTX-PG) in blast cells as a predictor of favorable treatment outcome in childhood acute lymphoblastic leukemia (ALL). We determined the expression of FPGS activity in blasts from children with ALL at diagnosis and after treatment with MTX as a single agent, before conventional remission induction therapy. The levels of enzyme activity in ALL blasts at diagnosis (median of 689 pmol/h/mg protein) were significantly higher (P = .003) than those found in acute nonlymphoblastic leukemia (ANLL) blasts (median of 181 pmol/h/mg protein). Comparable lineage differences in normal lymphoid versus nonlymphoid cells suggest a lineage-specific control of FPGS expression, FPGS activity increased in ALL blasts after in vivo exposure to MTX. The median increase in FPGS activity was significantly higher (P = .003) in B-lineage ALL (188%) than in T-lineage ALL (37%). Likewise, the percentage of intracellular long chain MTX-PG (Glu3-6) was significantly higher (P = .02) in B- lineage ALL (92%) than in T-lineage ALL (65%), consistent with higher FPGS activity in B-lineage blasts. This finding could explain, at least in part, the superior outcome in children with B-lineage ALL treated with antimetabolite therapy.  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