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441.
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444.
Stark DD; Wittenberg J; Edelman RR; Middleton MS; Saini S; Butch RJ; Brady TJ; Ferrucci JT Jr 《Radiology》1986,159(2):365-370
Forty-three patients with liver metastases were imaged using 14 different pulse sequences (average, 7.5 sequences per patient) to allow direct comparison of their performance. "T2-weighted" spin-echo (SE) images, "T1-weighted" inversion recovery (IR) images, and "T1-weighted" SE images were obtained using a wide range of timing parameters. Pulse sequence performance was quantitated by measuring liver signal-to-noise (S/N) ratios and cancer-liver signal difference-to-noise (SD/N) ratios. Data were standardized to reflect a constant imaging time of 9 minutes for all pulse sequences. The SE 2,000/120 (TR [repetition time]/TE [echo time]) sequence resulted in the greatest SD/N ratio of the T2-weighted SE sequences but also yielded the low S/N ratios, poor anatomic resolution, and motion artifacts common to all T2-weighted SE images. IR sequence images were also sensitive to motion artifacts because of the use of a long TR (1,500 msec). Short TR/TE T1-weighted SE sequences (SE 260/18) had the greatest SD/N ratio (P less than .05), S/N ratio, and anatomic resolution. Furthermore, extensive signal averaging appears to be a powerful solution to all types of motion artifacts in the abdomen. 相似文献
445.
Functional analysis of Gscl in the pathogenesis of the DiGeorge and velocardiofacial syndromes 总被引:1,自引:1,他引:1
Wakamiya M; Lindsay EA; Rivera-Perez JA; Baldini A; Behringer RR 《Human molecular genetics》1998,7(12):1835-1840
Gscl encodes a Goosecoid-related homeodomain protein that is expressed
during mouse embryogenesis. In situ hybridization and immunohistochemistry
studies show that Gscl is expressed in the pons region of the developing
central nervous system and primordial germ cells. Gscl expression is also
detected in a subset of adult tissues, including brain, eye, thymus,
thyroid region, stomach, bladder and testis. Gscl is located within a
region of the mouse genome that is syntenic with the region commonly
deleted in DiGeorge and velocardiofacial syndrome (DGS/VCFS) patients.
DGS/VCFS patients have craniofacial abnormalities, cardiac outflow defects
and hypoplasia of the parathyroid gland and thymus due to
haploinsufficiency of a gene or genes located within the deleted region.
Thus, the genomic location of Gscl and its expression in a subset of the
tissues affected in DGS/VCFS patients suggest that Gscl may contribute to
the pathogenesis of DGS/VCFS. To determine the role of Gscl during mouse
embryogenesis and in DGS/VCFS, we have deleted Gscl by gene targeting in
mouse embryonic stem cells. Both Gscl heterozygous and Gscl null mice were
normal and fertile, suggesting that Gscl is not a major factor in DGS/VCFS.
Interestingly, expression of the adjacent Es2 gene in the pons region of
Gscl null fetuses was absent, suggesting that mutations within the DGS/VCFS
region can influence expression of adjacent genes. In addition, embryos
that lacked both Gscl and the related Gsc gene appeared normal. These
studies represent the first functional analysis of a DGS/VCFS candidate
gene in vivo. These Gscl null mice will be an important genetic resource
for crosses with other mouse models of the DGS/VCFS.
相似文献
446.
Schell U; Wienberg J; Kohler A; Bray-Ward P; Ward DE; Wilson WG; Allen WP; Lebel RR; Sawyer JR; Campbell PL; Aughton DJ; Punnett HH; Lammer EJ; Kao FT; Ward DC; Muenke M 《Human molecular genetics》1996,5(2):223-229
Holoprosencephaly (HPE) is a common developmental defect involving the
brain and face in humans. Cytogenetic deletions in patients with HPE have
localized one of the HPE genes (HPE2) to the chromosomal region 2p21. Here
we report the molecular genetic characterization of nine HPE patients with
cytogenetic deletions or translocations involving 2p21. We have determined
the parental origin of the deleted chromosomes and defined the HPE2
critical region between D2S119 and D2S88/D2S391. As a first step towards
cloning the HPE2 gene which is crucial for normal brain development we have
constructed a YAC contig which spans the smallest region of deletion
overlap. Several of these YACs could be identified which span three
different 2p21 breakpoints in HPE patients. These YACs narrow the HPE2
critical region to less than 1 Mb and are now being further analyzed to
identify the gene causing holoprosencephaly on chromosome 2.
相似文献
447.
T P Pretlow R W Grane P L Goehring A S Lapinsky T G Pretlow 《Laboratory investigation; a journal of technical methods and pathology》1987,56(1):96-100
F344 Male rats weighting between 90 and 110 gm were given 90 ppm diethylnitrosamine in their drinking water for 5 weeks. Seven weeks after the administration of carcinogen was completed, the rats were sacrificed and sections of their livers were embedded in methacrylate. Serial sections 2 or 4 micron in thickness demonstrated the presence of gamma-glutamyl transpeptidase, acid phosphatase, adenosine triphosphatase, aldehyde dehydrogenase, alkaline phosphatase, alpha-naphthyl butyrate esterase, DT diaphorase, glucose-6-phosphate dehydrogenase, and 5'-nucleotidase activity and glycogen. The use of 4-micron sections of methacrylate-embedded tissue allows the evaluation of many more phenotypic markers in serial sections than is currently possible with frozen sections. 相似文献
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450.
Yeoman RR; Sonksen J; Gibson SV; Rizk BM; Abee CR 《Human reproduction (Oxford, England)》1998,13(9):2527-2531
Assisted reproductive techniques require an efficient semen collection
procedure in cases of ejaculatory dysfunction. Anejaculation may be of
psychogenic or neurogenic origin but can be overcome with stimulatory
techniques. Penile vibratory stimulation (PVS) therapy for anejaculation
has recently emerged as an alternative to rectal probe electroejaculation
(RPE) and more invasive testicular procedures. Comparison of the
stimulatory procedures in neurologically intact subjects is not ethically
possible due to the discomfort involved with electroejaculation, and
comparison in spinal cord injured men may be compromised due to the
intricate effects of chronic denervation on semen quality. We have
previously shown the efficacy of PVS in a non- human primate, the squirrel
monkey. A cross-over study design comparing semen collected by PVS and RPE
was employed during the breeding season in which 15 donor males were
divided into two groups. One group received PVS and the other RPE, then,
three days later, treatments were reversed. Twelve of 15 animals responded
to PVS (80%), all with spermatozoa in the ejaculate. Mean volume (436 +/-
90 microl), motility (80.6 +/- 4.3%), and total spermatozoa (32.8 +/- 10.2
x 10(6)) were significantly higher than in the semen after RPE. RPE
resulted in ejaculation in all 15 animals with a semen volume of 205 +/- 25
microl, but fewer samples contained spermatozoa (9/15) resulting in a low
total count (0.5 +/- 0.3 x 10(6)). The motility was reduced in those
samples with spermatozoa (n = 9; 44.1 +/- 11.4%). Additionally, accessory
gland activity was measured via the seminal vesicle and prostrate markers,
fructose and citric acid, respectively. The PVS specimens had significantly
more fructose (2.9 +/- 0.7 mg/ejaculate) and citric acid (0.46 +/- 0.14
mg/ejaculate) compared to RPE collected specimens (1.2 +/- 0.3 mg/ejaculate
and 0.24 +/- 0.04 mg/ejaculate, respectively). In conclusion, PVS produces
a much greater sperm yield and increased accessory gland secretion compared
to RPE in our neurologically intact squirrel monkey model.
相似文献